I'm kinda torn on my answer to this. I grew up mainly playing Sega systems: Master System, Genesis, Game Gear, Dreamcast. My friends did too for the most part. From time to time, I'd hang out with a friend that had an NES or an N64 or whatever. I guess out of all the Nintendo systems, I would say I liked the NES game selection the most. However, I was totally content playing my Master System games...Space Harrier 3-D & Missile Defense 3-D were something no NES gamer could match! Not to mention that Sega's controllers typically made sports games easier to play, which is still my favorite genre of games.
To answer the question: NES