Compared to what we have today the NES is totally showing it's age. But if you want my two cents or even if you don't want my two cents... here's the games I think are worth playing for the NES -
Solar JetMan - it's basically a skill game. You might get frustrated with it but once you learn it, it is quite rewarding.
RC Pro Am - yeah, the best racing game on NES in my opinion. Controls are tight but I don't think you should be able to shoot other cars. LOL! that was a funny addition to this game.
Tecmo NBA Basketball - too easy to make shots but a great game. Captures the strategies of basketball quite well which was "a first" in a video game.
Defender Of The Crown - a great game really. Might actually hold up to some of the games of today as far as gameplay goes. And there was an updated XBOX version of this game called Robin Hood: Defender Of The Crown but I never got a chance to play it.
Quatrro Sports - it's basically 4 sports games on one cartridge but the tennis game is the only one worth playing. It was the first tennis game I ever saw where you could actually put direction on the shot.
World Cup Soccer - it's good for a few laughs but not exactly a great game.
Spy vs Spy - a really fun multiplayer game but was kind of lacking in single player.
Skate Or Die - This might be the best sports game on NES to be honest.
North And South - Nice blend of action and strategy in this civil war game.