As for me, I want King Kai but I think that I found a good one in the old days but I lost it.
Then: Appolo Justice, Himawari the ninja, And Inazuma eleven characters

When I briefly tinkered with winmugen I vividly remember a version of Jacket Shadow DIO with a silhouetted TheWorld and with the supers of both normal DIO and the shadow one as well as all sorts of weird combos. I tried using him in 1.0 and he had mad helper clone issues lmao. Unfortunately never found it after my last rig broke and I lost my previous builds. It'd be cool to find a modern conversion of him (I even checked JJBA Requiem and the april fools dio-only version, no luck there either)

Sleeper pick but I hope eventually someone makes a GSR or custom styled Kaguya Houraisan. The old hisou style one and the cheap type moon Kaguya aren't as well-made as newer 2hu chars sadly

A proper Z2i Vegito would be great too. Might try my hand at that eventually

The Rivals of Aether versions of Anne Boonchuy and Luz Noceda needed to be MUGENized at all costs

Martlet from undertale yellow