Don't know yet.
I was thinking Jun the Swan, Holly Summers, or Vergil. Might hold off on Vergil until UMvC3 comes out though, the model from it should be better.
Jun sounds kickass. More Tatsunoko is never a bad thing.
Who the hell is Holly Summers? *googles her* Oh, NMH. Looks cool.
Vergil would also be kickass. That vertex hack of him is OK, it doesn't quite do him full justice.
You know, I know you're not taking requests or anything, but if you want to make a DMC character and can't wait until UMvC3 gets released, there's always the option of doing someone like Nero or Sparda. Just saying...