N64 for the first console I bought myself with summer job $$$$. It wasn't amazing, though it was great for the time. I still, and always have preferred 2D sprite-based gaming. But N64 had some really great games. Gamecube was another matter for me. I never bought one myself. I was going to, late in it's life, for Twilight Princess, because the GC version of TP is the version I had been waiting years to play. But then when I realized Wii was going to be 100% backwards compatible, I said "fuck it" and just got a Wii (months later, when it was finally available), and got whatever GC games I liked or wanted for Wii instead.
GC had some great games that I still love to this day, like Pikmin, Metroid Prime, Eternal Darkeness, Chibi Robo, Waverace: Blue Storm, the RE1 remake, etc., but it also had several entries in my fav. franchises that I either just didn't care about, or outright hated, such as Mario Sunshine, Wind Waker, Mario Kart: Double Dash, and Star Fox: Assault.
N64, on the other hand, had Mario 64, Ocarina of Time, Goldeneye, Turok 2, the best port of NBA Hangtime, Duke Nukem 64, Doom 64, Mario Kart 64, a good port of MK Trilogy (except for the unacceptably bad music), Wave Race (which was mind blowing for it's time), Beetle Adventure Racing, KI Gold, Blast Corp, Body Harvest, Mischief Makers, Tetrisphere...............I mean it had some really great games, even though it had it's issues as well. I would say, overall, the the N64, while the GRAPHICS certainly haven't aged well, had the larger volume of far greater games. Hell, just for Mario Kart 64 and Goldeneye alone, the fact that some friends and I still tend to pick these games up once or twice a year and play them together, that says something. It was great system for multiplayer (obviously), and it had some genuinely good games.
NES is my fav. system of all time, and SNES is a close second, but N64 deserves a lot more respect than some people tend to give it.