1) Castlevania 3 - Overall best presentation, best difficulty and many memorable characters to play as.
2) Zelda - A link to the past (gets the zelda spot cuz of length, story and the variable difficulty)
3) Mario Bros. 3 (All releases)
4) Ninja Gaiden Nes version (feels like an interactive film)
5) Nes Metroid - hard and well balanced with the varia suit option as a handicap instead of a necessity.
6) FF VII - Best one, but the main boss should be hard like the first.
7) Onimusha 2 - Amazing 3d adventure, love the gift system and the difficulty was balanced amazingly well.
Megaman 2 - best megaman with the most variety in weapons and the ability to alter the difficulty to suit the player.
9) Grand Theft Auto Vice City - best GTA so far with the highest replayability and the addition of rock station was nice.
10) Nes Super Contra - best Contra so far (though I've yet to finish 4 due to time restraints so this one may change)
Runner up - Space Invaders (all releases). Gotta love vaporizing scores of aliens with one ship.