Okay! I've only done so for the Wii, so here goes!
Super Metroid (SNES): Must've played through this game a dozen times or more trying to unlock the damn best ending, with Samus decked out all skimpy like. The atmosphere, music, and gameplay remain in my mind the best that the SNES had to offer, which makes it a runner for a top 10 list in the future, should I ever compile one.
TMNT (NES): Honestly thought it wasn't as bad as Angry Video Game Nerd would have you believe, although there is a great deal of the game that was really poorly thought out, such as level design, or enemy placement.
Sonic the Hedgehog 2 (Genesis): Only downloaded it because I remember the music being really awesome. Gameplay has held up to standards in my opinion, but I rarely go back to it for whatever reason.
Streets of Rage (Genesis): Yuzo Koshiro's excellent score aside, this game has aged really badly. Gameplay is not as fast as I remember it being, also being more shallow too. My memories of this game are far more awesome than the game itself.
Starfox 64 (N64): Probably one of my most loved titles for the N64. Downloaded it to try and get the medals on each planet, but have thus far only succeeded in acquiring the one for Corneria. Loved the music, too.
Paper Mario (N64): Downloaded this for the missus. She plays it more than I do, and as much as I adored the Gamecube and Wii iterations of the series, I doubt I'll ever actually see this one through to the end.
As for what I want? Ocarina of Time, mostly. If they ever get around to doing the NES Megamans, sure, why not? I just really want the SNES RPG's I remember fondly, like (Insert any Squaresoft game here), or Earthbound, or Breath of Fire (with redone translations, if possible, for God's sake), you know. What have you.