3D Donkey Kong (or 2D DKC, either works, these guys did make the original DKC games after all). But yeah, 3D DK would be ideal. Donkey Kong needs a second chance at 3D platforming. DK64 was... well, it was okay... But you gotta admit it could have been so much better, both as a game on its own, and as a Donkey Kong game. I think these guys could pull it off.
Just imagine. A new 3D Donkey Kong that has both David Wise and Grant Kirkhope composing!! And don't forget a new DK Rap!