2D Sonic has indisputably performed better over the years. However, I think this is because it's easier to make a 2D Sonic game good, not because 2D is inherently better suited to Sonic. I think 3D Sonic has more potential to produce the best Sonic game ever, if they'd just get it right, but thus far they haven't. I have high hopes for Sonic Boom, though, it seems to be doing a lot of things right, let's hope they really are though and it doesn't just seem that way until we actually get the game in our hands.