I'm gonna do some bizarro posting here.
Sonic 3D Blast is a great game. Screw the haters, the game does its purpose and plays quite well, the way it's supposed to. And for an isometric Sonic game, it's pretty cool.
Sonic 2, I consider the worst-looking of the Genesis titles. Seriously, they got rid of the crisp, clear look of Sonic 1 and made everything look more plastic-y. Reminds me of the change of models between Sonic Adventure and Heroes.