Sonic Adventure
Sonic Adventure 2: Battle
Sonic Heroes
Sonic Riders
Sonic Unleashed
Sonic Generations
Sonic The Hedgehog (2006) (I don't care what anyone says, this was my baby. I had no glitches or anything and it worked perfectly and everything flowed together well. It stopped working so I cried. )
Sonic Battle
Sonic Advance 3
Sonic Rush

I love Sonic.

Sonic Heroes. Each stage was epic.

Sonic Adventure 2 Battle, Sonic DX (Director's Cut), Sonic Heroes, and Sonic the Hedgehog (2006).

I like Sonic Colors & Generations. The originals were great as well. I can't stomach to play them now, though. Especially with those graphics.

Sonic Heroes lol.

omg sonic spinball for the Sega Genesis

I remember playing one on Sega Genesis when I was young with my cousins and still have great memories of it.

Definitely Sonic The Hedgehog 2. I got that X-Box game where you can play all the different Sonic games, which is really cool. Brings back so many memories of the game. I even downloaded the music soundtrack for it too since I grew up playing the video game and hearing the music all the time.

The trinity:

Sonic Heroes - just a childhood game.
Sonic Adventure 2 Battle - see above, but chao were also EVERYTHING to me.
Sonic Riders (the whole series) - a really fun racing series tbh.

Sonic Battle for GBA.