Spoiler:
孫悟空 (Son Gokuu): Not much to say here. I use "Son Goku." Pretty much nobody uses it anymore, but I have to say that I strongly dislike the old "Gokou" spelling seen on old merchandise. I know it's using a French "ou" (for some reason), but to me it just looks like "Go-ko."
ブルマ (Buruma): I use Bulma. Not for any logical reason, just because I grew up with it. Some people use "Blooma," using the logic that "buruma is to burumaa what Furiiza is to Furiizaa." That's not exactly right though. "Buruma," although it comes from the English "bloomers," is a real word in Japanese, unlike Freeza, and from what I've seen is more common than "burumaa," although both spellings are generally interchangeable. The word doesn't refer to what we think of as "bloomers" but actually means girls' gym shorts. The version with the extended vowel (burumaa), from what I know, can refer to both the gym shorts and the English definition of "bloomers." If wouldn't mind "Bloomers" or "Buruma," but to me Blooma seems a bit extreme for such a shaky reason.
亀仙人 (Kame Sennin) / 無天老師 (Muten Roushi): For the first I most often use "Kame Sennin" (no apostrophe), although "Turtle Hermit" or even "Turtle Sage" or "Turtle Immortal" (from usual translation I see of Chinese 仙人) would be preferable for me to see in an official translation. Translating the "muten" in "Muten Roushi" is probably impossible to do without pissing off somebody (No-Heaven Teacher? Heavenless Teacher?? ), so I usually leave it as just "Muten Roshi" (macron optional, contrary to how I usually romanize things, but you can thank the Funi dub for brainwashing me into thinking that "roshi" is an acceptable romanization of ろうし ).
ウーロン (Uuron): I use the anglicized name for the tea, "Oolong", although it wouldn't bother me if someone used "Wulong" or "Wu-lung" instead.
ヤムチャ (Yamucha): I'm leaning towards the common anglicized version of the Cantonese term, "Yum Cha," nowadays. The Yale romanization "Yam Chah" might replace it one day, if I find out what the lead romanization system of Cantonese is (there's a lot of them). There's no way I can use the Jyutping "Jam Caa" or Cantonese Pinyin "Jam Tsaa" without giving people headaches. I really don't like that the official subs use "Yamucha," one of the few problems I have with the Funi subs.
プーアル (Puuaru): I'm contradicting myself in regards to Oolong, since I use the Hanyu Pinyin "Pu'er" for this little guy instead of the more common name for the tea in English, "Pu-erh" (from the Wade-Giles "P'u-erh"), but I just think that "h" at the end looks ugly, I'm sorry.
牛魔王 (Gyuumaou): Due to common fandom usage, I usually use some variation of "Gyuumaou" or "Gyuumaoh" or what have you. I'd prefer an official translation to just translate it though. I don't know what the Anthony Yu translation of Journey to the West uses for Niu Mowang, but I've seen it translated as "Bull Devil" in a kung fu movie once. That would be okay, I guess.
神龍 (シェンロン Shenron): Like the majority of fans on this site, I use the Hanyu Pinyin "Shenlong" (some use spaces) rather than "Shenron" (or the Wade-Giles "Shen-Lung").
クリリン (Kuririn): I go back and forth between Kuririn and Krillin. Never cared for "Kulilin" or "Klylin," but nobody uses those anyway. (This is off-topic, but I'd use the Mandarin "Duolin Temple" for 多林寺 (Oorin-ji) instead of "Oorin." We use "Xiaolin" in English after all, not "Shourin." This is something that only seems to bother me, though, since it's so minor.)
ランチ (Ranchi): I use "Lunch," like most people here. Not much new to say with this one. "Lunch" goes with the food theme a lot of characters have, while "Launch" is seemingly random. Who knows what Toriyama was going for though. If he came out one day and said he had the image of a firing rocket in mind when he created her, I would change my position.
桃白白 (タオパイパイ Taopaipai): I use the Pinyin "Tao Baibai." Some use spaces (Tao Bai Bai), but I don't since it's weird to split up his given name (you usually see "Mao Zedong," not "Mao Ze Dong"). From what I see most people use a hyphen-less Wade-Giles spelling (Tao Pai Pai instead of Tao Pai-Pai), or a smushed together Wade-Giles spelling, in possible imitation of Pinyin (Tao Paipai), although maybe that just comes from the Japanese. This guy's name is a huge can of worms, basically.
餃子(チャオズ Chaozu): I prefer "Jiaozi," but I usually use the Wade-Giles "Chiao-tzu" since people unfamiliar with Pinyin romanization will most likely mangle the pronunciation with the Pinyin spelling. "Huh? Who's this 'Jaozee' guy?"
神様 (Kami-sama): I use "God." That's what it means, no point in beating around the bush.
カカロット (Kakarotto): I use "Kakarrot." I don't use c's because "carrot" in Japanese is "kyarotto," not "karotto." You can't differentiate using the a/ya part in English so using a k gets across the fact that it's spelled weird, and not just the word "carrot" with a doubled syllable. The rest of the word is spelled the same as "carrot" since they're spelled the same in Japanese, too (Kakarrot and carrot vs. カカロット and キャロット)
人造人間 (jinzou ningen): This is a group of characters, so I'm going to say it counts. I use "android(s)", since it's a perfectly fine translation. "Artificial Human" just seems like an unnecessarily literal calque to me. Jinzou Ningen isn't a unique term from Dragon Ball, after all. Although in Japan they sometimes use "andoroido," "jinzou ningen" (literally man-made human) is a synonym. If you want to look up androids on the Japanese Wikipedia, for example, the article is called "jinzou ningen," with "andoroido" as a redirect. Yes, I know that 17, 18, and 20 are actually cyborgs, but it makes just as little sense in Japanese, since Cyborgs are called "saiboogu" or "kaizou ningen" (modified humans; same "kai" as in "Dragon Ball Kai"), never "jinzou ningen". Toriyama just messed up.
魔人ブウ (Majin Buu): I use the double-"u" spelling because of exposure via Funimation. Although I like the "Boo" spelling too. The "u" spelling is just what I default to. I honestly have no problem with Viz's "Djinn Boo" translation, since Djinni/Jinni/Genies are sometimes called "majin" in Japanese. Plus there's that line about what Trunks expects a "majin" to look like, and Buu wears vaguely Arabian clothes, so him being a genie is probably what's intended. I also used to know this Muslim guy in middle school who would half-jokingly refer to him as "Buu the Genie," so there's that too, I guess.
ブルマ (Buruma): I use Bulma. Not for any logical reason, just because I grew up with it. Some people use "Blooma," using the logic that "buruma is to burumaa what Furiiza is to Furiizaa." That's not exactly right though. "Buruma," although it comes from the English "bloomers," is a real word in Japanese, unlike Freeza, and from what I've seen is more common than "burumaa," although both spellings are generally interchangeable. The word doesn't refer to what we think of as "bloomers" but actually means girls' gym shorts. The version with the extended vowel (burumaa), from what I know, can refer to both the gym shorts and the English definition of "bloomers." If wouldn't mind "Bloomers" or "Buruma," but to me Blooma seems a bit extreme for such a shaky reason.
亀仙人 (Kame Sennin) / 無天老師 (Muten Roushi): For the first I most often use "Kame Sennin" (no apostrophe), although "Turtle Hermit" or even "Turtle Sage" or "Turtle Immortal" (from usual translation I see of Chinese 仙人) would be preferable for me to see in an official translation. Translating the "muten" in "Muten Roushi" is probably impossible to do without pissing off somebody (No-Heaven Teacher? Heavenless Teacher?? ), so I usually leave it as just "Muten Roshi" (macron optional, contrary to how I usually romanize things, but you can thank the Funi dub for brainwashing me into thinking that "roshi" is an acceptable romanization of ろうし ).
ウーロン (Uuron): I use the anglicized name for the tea, "Oolong", although it wouldn't bother me if someone used "Wulong" or "Wu-lung" instead.
ヤムチャ (Yamucha): I'm leaning towards the common anglicized version of the Cantonese term, "Yum Cha," nowadays. The Yale romanization "Yam Chah" might replace it one day, if I find out what the lead romanization system of Cantonese is (there's a lot of them). There's no way I can use the Jyutping "Jam Caa" or Cantonese Pinyin "Jam Tsaa" without giving people headaches. I really don't like that the official subs use "Yamucha," one of the few problems I have with the Funi subs.
プーアル (Puuaru): I'm contradicting myself in regards to Oolong, since I use the Hanyu Pinyin "Pu'er" for this little guy instead of the more common name for the tea in English, "Pu-erh" (from the Wade-Giles "P'u-erh"), but I just think that "h" at the end looks ugly, I'm sorry.
牛魔王 (Gyuumaou): Due to common fandom usage, I usually use some variation of "Gyuumaou" or "Gyuumaoh" or what have you. I'd prefer an official translation to just translate it though. I don't know what the Anthony Yu translation of Journey to the West uses for Niu Mowang, but I've seen it translated as "Bull Devil" in a kung fu movie once. That would be okay, I guess.
神龍 (シェンロン Shenron): Like the majority of fans on this site, I use the Hanyu Pinyin "Shenlong" (some use spaces) rather than "Shenron" (or the Wade-Giles "Shen-Lung").
クリリン (Kuririn): I go back and forth between Kuririn and Krillin. Never cared for "Kulilin" or "Klylin," but nobody uses those anyway. (This is off-topic, but I'd use the Mandarin "Duolin Temple" for 多林寺 (Oorin-ji) instead of "Oorin." We use "Xiaolin" in English after all, not "Shourin." This is something that only seems to bother me, though, since it's so minor.)
ランチ (Ranchi): I use "Lunch," like most people here. Not much new to say with this one. "Lunch" goes with the food theme a lot of characters have, while "Launch" is seemingly random. Who knows what Toriyama was going for though. If he came out one day and said he had the image of a firing rocket in mind when he created her, I would change my position.
桃白白 (タオパイパイ Taopaipai): I use the Pinyin "Tao Baibai." Some use spaces (Tao Bai Bai), but I don't since it's weird to split up his given name (you usually see "Mao Zedong," not "Mao Ze Dong"). From what I see most people use a hyphen-less Wade-Giles spelling (Tao Pai Pai instead of Tao Pai-Pai), or a smushed together Wade-Giles spelling, in possible imitation of Pinyin (Tao Paipai), although maybe that just comes from the Japanese. This guy's name is a huge can of worms, basically.
餃子(チャオズ Chaozu): I prefer "Jiaozi," but I usually use the Wade-Giles "Chiao-tzu" since people unfamiliar with Pinyin romanization will most likely mangle the pronunciation with the Pinyin spelling. "Huh? Who's this 'Jaozee' guy?"
神様 (Kami-sama): I use "God." That's what it means, no point in beating around the bush.
カカロット (Kakarotto): I use "Kakarrot." I don't use c's because "carrot" in Japanese is "kyarotto," not "karotto." You can't differentiate using the a/ya part in English so using a k gets across the fact that it's spelled weird, and not just the word "carrot" with a doubled syllable. The rest of the word is spelled the same as "carrot" since they're spelled the same in Japanese, too (Kakarrot and carrot vs. カカロット and キャロット)
人造人間 (jinzou ningen): This is a group of characters, so I'm going to say it counts. I use "android(s)", since it's a perfectly fine translation. "Artificial Human" just seems like an unnecessarily literal calque to me. Jinzou Ningen isn't a unique term from Dragon Ball, after all. Although in Japan they sometimes use "andoroido," "jinzou ningen" (literally man-made human) is a synonym. If you want to look up androids on the Japanese Wikipedia, for example, the article is called "jinzou ningen," with "andoroido" as a redirect. Yes, I know that 17, 18, and 20 are actually cyborgs, but it makes just as little sense in Japanese, since Cyborgs are called "saiboogu" or "kaizou ningen" (modified humans; same "kai" as in "Dragon Ball Kai"), never "jinzou ningen". Toriyama just messed up.
魔人ブウ (Majin Buu): I use the double-"u" spelling because of exposure via Funimation. Although I like the "Boo" spelling too. The "u" spelling is just what I default to. I honestly have no problem with Viz's "Djinn Boo" translation, since Djinni/Jinni/Genies are sometimes called "majin" in Japanese. Plus there's that line about what Trunks expects a "majin" to look like, and Buu wears vaguely Arabian clothes, so him being a genie is probably what's intended. I also used to know this Muslim guy in middle school who would half-jokingly refer to him as "Buu the Genie," so there's that too, I guess.