I think 'the Legend of Zelda: a Link to the Past' is the best retro game. Not only is it my personal favorite SNES game but it was a masterpiece in game design for its time even if it isn't known for being one or referredto as one, Nintendo did an insanely amazing job with it.
Sonic 3 and Knuckles hands down is the best retro game. The soundtrack is awesome, the new abilities that Sonic, and Tails gained makes the game even more fun to play over Sonic 2. Plus the game introduced Knuckles to the franchise, and it's fun playing as him as he has his own level layouts.
