"new characer we had since Knuckles, was Shadow. That's pretty much it."
Shadow is not exactly the best character. What the heck happened to the bright ol days of Sonic 1. Now it's all gritty urban cities and guns.
Also sonic team have introduced new characters from sonic 2, well technically from sonic 1 because they indroduced sonic and robotnik then
sonic 2: tails
sonic 3: knuckles
sonic cd: amy
Knuckles chaotix: loads of dudes (that are all quite cool looking)
triple trouble: nack the weasel (or fang)
sonic advance 2: cream
sonic adventure: big and the robot
sonic adventure 2: shadow rouge
sonic rush: blaze
Best sonic games were definately Sonic 1, sonic 2, sonic 3 and sonic and knuckles.
Apart from those I can't say there have been any great sonic games. I use to think Sonic Adventure for dreamcast was cool, but thinking about it now - it was pretty cruddy.
Although imo Sonic 1 was the best - no storyline, no other characters intefering - just you blasting through the levels and kicking robotnik's ass