1) Sonic the Hedgehog 3 and Knuckles (GensX)
2) Yoshi's Island (XSnes9X)
3) Skitchen (GensX)
4) Super Tennis (XSnes9x) Just for two player competitiveness!
5) Mario Kart (XSnes9X)
This list ignores the PSX/N64 Generation because I haven't had a chance to fully play with these emulators yet (yeah, I know PCSXbox has been out for a while but work has been crazy lately), but if I were to include them, the following games would be on the list:
1) Wipeout 2097 or Wip3out/Special Edition (best games ever!)
2) Ridge Racer Type 4 (slick!)
3) Gran Turismo (still the most realistic feel of any racer except for GT3 on PS2)
4) Wipeout 64 (not sure if this will be playable)
5) Mario Kart 64 (2 player fun!)