Super Mario Bros. 3
Super C
Megaman 2
Super Mario Bros.
Mike Tyson's Punch-Out!
Super Mario Bros. 2
Teenage Mutant Ninja Turtles
Contra

Megaman 3
Blades of Steel
Legend of Zelda
Double Dragon II
Bubble Bobble

Baseball Stars 2 

9/14 games are third party. My, my how things changed for Nintendo. 

Some stories about the NES:

I was my first console ever, I first played it at a friend's house (Super Mario Bros.) and instantly started to nag my parents about getting one of our own. My constant demands worked and I got the console for Christmas.

Being way too young to have any money I played my games to death since the only time we would get new games would be at my birthday in April, at my brother's birthday in June and at Christmas. This is how I mastered games like Mega Man 2 and Battletoads.

Also, having to depend on my parents meant I didn't always get exactly what I asked for... I received Zelda II: The Adventure of Link when I asked for the original and after playing an imported version of Super Mario Bros 3 at a friend's house and describing it to my mother, she somehow manage to find an imported version of Super Mario 2 Japan (which would later be released as the Lost Levels on SNES). I never told her it wasn't the right game because I knew she went through a lot of trouble to find that in our remote northern Quebec town.

ive only gotten to play NES games through Virtual Console but from that I have loved the original Super Mario Bros. imo its still the best one they ever made

From what I have played mostly on emulators I would say:

1. Mario Bros 3
2. Kirby's Adventure
3. Megaman 2
4. Mario Bros
5. Metroid
6. Ducktales
7. Legend of Zelda
8. Mario Bros 2
9. Ninja Gaiden
10. Castlevania III

1 - Super Mario Bros 3
2 - Mega Man 2
3 - Battletoads
4 - Legend of Zelda
5 - Mega Man 4

Honorable mentions: Super Mario Bros, Contra, Balloon Fight...

Yeah I'm not sure either. Doesn't really matter to me either way, I like story-time so you'll see me every day at least.

The Guardian Legend.
Why does this game gets no more attention?

I was born a solid 15 years too late to grow up with a nes but out of the stuff I've gone back and played I probably have to go with kid Icarus as my absolute favorite. The original super Mario Bros and Zelda 2 are also up there

Super Mario Bros 3 is my pick

Mario Bros 3, Mega Man 2, Mega Man 3, Castlevania, Double Dragon. Those are the games that come to my mind right now.