Its a bit silly to say the GC had more games when N64 had Mario and Zelda that changed gaming.
These are generational games. The GCN had none.
It's silly to judge a library solely on either quality or quantity, when one thing is sorely missing. Which is the case for N64. Even if it had three game changers (SM64, OoT, Goldeneye), there's select genres on SNES or PS1 that had more must-have titles than N64 in its entirety. Speaking of genres, some didn't even exist on N64 outside of a handful of JP-only titles. Imagine not liking platformers or FPS. Then like one third of the N64 library turns useless.

Not so much on GCN. And even if the games didn't have the impact of OoT, what did anyway? Maybe Halo? There's only so much you can innovate the industry - GCN still had some of the best games of the gen, plus some of the best graphics that often still look good today (hell, the recent Luigi's Mansion 3DS port was
downgraded 
). It wasn't Zelda or classic Mario for a change that was the top-tier, but that is refreshing anyway. You had quality entries of almost everything that existed on N64, more genres (RPG, strategy, horror...), better 3rd party deals, crazier concepts and new IPs which didn't all come from Rareware and of which several became mainstays.