I actually like the 3D style better, though I've admittedly only played one of the 2D games, and Sonic Adventure 2 Battle was one of my favorite gamecube games ever played. The story was a bit silly, but it worked. The gameplay was a blast, and chaos are the greatest thing since sliced bread. Actually, if they ever bring back the Chao Garden, I'd buy another Sonic game in a heartbeat. Still one of the most absurdly addicting mini games/side quests I've ever come across in a game.
Hmm