Favorite: Baseball Stars - The countless hours I spent playing this with my father were some of the greatest memories of my youth. He spent plenty of nights doing the money trick (Create a team with all guys with just prestige, use that team against your created team, walk everyone in, 10 run rule, get cash) in order to have his own team full of maxed out all stars. (Considering you could get like 45k per game, and how much those maxed out players cost... do the math. The man worked. Saddest memory was when I went to play, and the NES CLEARED THE BATTERY SAVE. I don't think we played it again after that.)
Tecmo Super Bowl - I mean, c'mon. Pure console bliss.
Castlevania - 2D Castlevania games are still incredibly good this day. Who needs 3D?
Mike Tyson Punch-Out - Why isn't a real updated version out for the Wii yet? Screw cooking mama, a new Punch-Out could be the perfect Wii game.
Excitebike - Being able to make your own tracks pushed this game up to the top.
Pro Wrestling - Starman was a beast. Fighter Hyabusa was useless. The game... a classic.
SMB 1-3, yes, 2 was great as well. Huge Doki Doki Panic fan.