just found this thread now, I came here so late but here's my opinion, for me Shintani just wins easily, I got so much suprised in that teaser with the art style, I love how Ryo Onishi made it looks like even Fighter Z in that first teaser, but with less 3D a bit, i just loved his Goku's design, is very similar to Maeda's skinny Goku from the Majunior/23rd Tournament Saga, with a bit of Nakatsuru's design, I'm so glad Vegeta's real look is finally back, I missed a lot his big forehead, and specially his large astern spiked hair, also his real body structure, he's finally skinny again, now Piccolo is definitely my favorite from the new design, my gosh thank you Shintani, for me Yamamuro's Piccolo is just horrendous, I just hate how always looks like that Yamamuro's Piccolo is awfully drawned, those poor drawned eyebrowns, little ears, that large chin, always annoyed me, I'm so glad they finally changed it, for me would be perfect if they had back to Piccolo's Majunior original first design from the 23rd Tournament saga, yeah that skinny Piccolo with those giant eyes, ears, he was my favorite, but I'm happy with Shintani's Piccolo! I love other things too, I'm so happy that the exaggerated details, highlights and pitched/strong colors had finally gone, the Yamamuro's style starting from 2000's, for me got a fall, at least the Budokai 2 & 3 openings were gorgeous, I think his fall was when the Gaiden Remake came out, which he started to use the designs from that OVA often, seriously for me his design until the ending of Black Arc was atrocious, I hate how every character with muscles needs to have large necks in the sides, his Vegeta is just ugly, and why every character needs to be so square? if you didn't understand, look at Yamamuro's heads, they are so perfect squary! is so awful, when his style was beginned to be used often, who didn't missed Minoru Maeda's classic oval curves in the characters faces/heads?? for me Yamamuro should have kept his 2008 OVA designs for BoG, RoF and Super, his design in that OVA for me is his best, is a mix of himself with Toriyama, that design don't have the boring exaggerated details, highlights, pitched/strong colors, the characters still are pretty square, but the squares were decreased and now is way better, so bad that design was exclusive, I think Yamamuro's design at least was increased in the ToP, his work in the previous sagas is just horrendous, for me specially in Black saga, but if you look in ToP, it even looks like Buu Saga, but still needed improviments, Yamamuro's design for Buu saga was definitely my favorite, just perfection, the SSJ's hair is now a real golden color, specially in the movies.
my ratings:
Shintani - 9.0
Yamamuro (2000-2016) - 5.0
Yamamuro (2017-Now) - 7.0
Yamamuro (1993-1996) - 10
Yamamuro (2008) - 8.5
Minoru Maeda - 9.5
Nakatsuru - 9.0

I simply wouldn't want to imagine my life without Dragon Ball, thank you Akira Toriyama (1955-2024), you are now immortal ~☆