About the topic... I love the original trilogy.
I played them a lot of times when I was younger, and I still enjoy them a lot.
But then there were the other games...
The two PSP games were mediocre at best, the NDS duology was good perhaps, but didn't achieve the "very good" rating, at least with me... they had several mistakes.
For Wii, I kinda liked Secret Rings, but didn't feel very Sonic to me, and Black Knight was overly short. Then, I liked Unleashed.
The PS2 and PS3 games were horrible (generally).
I loved the Episodes I and II of Sonic 4 for WiiWare, and also Generations, which I played on PC.
And the last Sonic I played was Colours, some months ago, and I really didn't like it. It felt like a step back from the various improvements of the previous titles (but still it was better than those games I labeled as horrible).
And now, as always, I'm expecting the next retro game... which would be Sonic 4: Episode III, or Sonic 5.