Which Sonic?

There are 3 different Sonic games by SEGA and I would like to know which one has better graphics and gameplay.

Sonic 1&2 are the good old faithfuls from ages ago. I like both of them. They are just like they were.
I am really enjoying Sonic 4 too. It is a lot more faithful to the earlier games than other recent Sonic releases. As far as Gameplay goes I think they are all worth a purchase. IMO Sonic 4 looks the best.