What's your favorate 2D/ 2.5D Sonic games?

I always just go to Sonic Mega Collection Plus. But there are some that aren't even on this game. Such as Sonic CD. Or Sonic Episode 4. 

Mega Collection Plus. On one offically licenced PS2 game you get most (maybe all?) Sonic games that originally released on the Segs Genesis and Sega Game Gear. 

Including Sonic 3D Blast -genesis- and Sonic Drift -gamegear-

I don't know of any other offical Sonic game bundles that come close in one collection. 

Sega went the extra mile and even included *some other Genesis games youd have to unlock.

i favorite is def Sonic's Ultimate Genesis Collection for the ps3 since that's what i used to play for the most part.

I remember wishing it had sonic cd included in it lmao

I wish instead of going for Full 3D Environment.

Sega's Sonic Team just went with 2D Sonic Game with nicer Polygonal Presentation for their Mainline Sonic Game on Sega Saturn like what's seen on "Clockwork Knight" with Futuristic Stages and other stuff and work on it the same time as Clockwork Knight and release it in Early 1995 and have it prepared for North American and European Sega Saturn Launch and call it "Sonic The Hedgehog 4" or "Sonic S".

Then test the waters with "Sonic X-Treme".