Club Nintendo

[PAOerfulone]

Speaking as someone who has played all 3D Sonic games, (except HD Unleashed and Boom), I'd say Colors and Generations were great.
The Adventure series, still decent, but haven't aged well.
Heroes, a pretty fair game itself as well, but still has its flaws. 
'06, I honestly think this isn't as bad as everyone says it is, defintely has its big problems, but it's not THAT bad. I managed to play through it just fine, and even enjoyed myself for the most part. (But FUCK the Ball Puzzle!)
The only 3D Sonic games that I can truly say were absolutely horrible and deserve every bit of flack that they get are Secret Rings and Shadow the Hedgehog.