Up until Sonic Adventure 1 the games were great. Although I think SA 1 was a great 3D Sonic, hands down for 2D Sonic because it´s much simple to play, still fast and also because of the roots of the series. From SA 2 onward the games had simply to much bullchit, unnecessary story elements/characters and complicated gameplay (ex. Sonic Heroes). The last great effort they made with Sonic imo was Sonic Generations.