I think most of us have played NES, personally the bests for me are Super Mario Bros II, KUNIO KUN NO NEKKETSU SOCCER LEAGUE and Saint Seiya II
Ok NES, let's see: Super Mario Bros. Super Mario Bros. 3 Blaster Master The Legend of Zelda Metroid Metal Gear Contra Mother Zelda II Final Fantasy Fire Emblem Dr. Mario Kid Icarus (at least to me) Kirby's Adventure Final Fantasy III Gyromite Though out of those ones, Kirby's Adventure and Super Mario Bros. hold a very special room in my heart. One because it's the best damn platforming world ever. The other, because it saved the world of videogaming of decadence and is the main pillar to what is today's videogaming industry.
SUPER MARIO World is undisputed champ of SNES games ever... click below to see this insane speed run of super mario world http://video.google.com/videoplay?docid=3460989542054644687
Its may not be the best but the one I hold nearest and dearest to my heart is Top Gun. It was the first game I ever played. As for my favorite game and most fun to play... it would have to be Sword Master or Mega Man