For Goku, it's a toss-up between his first SSJ transformation, just because of how unbelievably pissed-off he was. We had never seen him so furious, to the point where he wasn't sure he could even hold himself back against his own son, and the other moment is his SSJ3 transformation, just because of how epic the build-up was, it was really made of pure awesome.
Gohan's best moment, other than his obligatory SSJ2 transformation, was probably his pounding of third-form Freeza, and even final form Freeza on Namek. Sure, Freeza had powered down from 100%, but Gohan was still able to beat the tar out of him for just a brief moment. His rage boosts are always awesome to me.
Vegeta, also a toss up. First is when he becomes SSJ, and trounces C-19 effortlessly. That really showcased some major badassery for Vegeta, well before 18 made him her bitch. Second is Majin Vegeta at the Tenkaichi Budokai, partly because of the line, "tell me, is it slavery when you get what you want?" The way it was spoken was great.
Piccolo's fight with #17 was pretty awesome, and also, his fulfillment of killing Goku at the beginning of Z.
Trunks' best moment would have to be his introduction. He completely annihilates Freeza and Cold without breaking a single sweat, completely keeping his cool. (no pun intended).
Yamucha's best moment is probably when he doesn't die.
Actually, being able to fight off Oozaru Goku in original DB.Tenshinhan, probably holding off Cell. That was pretty cool. Even if he wasn't doing any real damage, he still put up a heck of a fighter considering how outclassed he was.
Kuririn's best, to me, was killing off pretty much all the rest of the Saibaimen in one shot.
What do you think?
