N64, because (in my opinion) Nintendo released subpar versions of a lot of my favorite franchises on the Gamecube...at least compared to their 64 counterparts. Paper Mario: The Thousand Year Door and Super Smash Bros. Melee were the only two of my favorite franchises that I thought improved on Gamecube. In comparison:
Wave Race 64 > Wave Race: Blue Storm
Ocarina of Time > Wind Waker (note that I haven't played Majora's Mask and won't unless a 3DS remake is made, and I generally consider Twilight Princess a Wii game since that was the system I played it on first. I DID play the Gamecube version of TP this past year, but I enjoyed the Wii version a bit more. Either way, OoT is superior to Wind Waker AND Twilight Princess...in my opinion at least, so N64 wins the Zelda comparison regardless)
Super Mario 64 > Super Mario Sunshine
Mario Kart 64 > Mario Kart: Double Dash
Star Fox 64 > Star Fox Adventures
In addition there were a lot of other N64 games I enjoyed, including quite a few 3rd-party games. Whereas Gamecube wound up being a 1st-party ONLY machine for me...more so than even Wii and Wii U. Don't get me wrong...as a proud, hardcore Nintendo fanboy, I have NO problem with buying a system knowing full well that I will buy and play mostly or even ONLY Nintendo's own 1st-party titles, but those titles need to be worth it. So far, Gamecube is the only Nintendo home console I've owned where I was consistently disappointed and let down by Nintendo's own offerings.
Upcoming Games To Get
Definite: Kirby Star Allies (Switch), Mario Tennis Aces (Switch), Fire Emblem (Switch), Yoshi (Switch), Pokemon (Switch), Kingdom Hearts 3 (PS4), Monster Hunter World (PS4)
Considering: Fe (Switch), Donkey Kong Country Tropical Freeze (Switch), The World Ends With You (Switch), Ys VIII (Switch), Street Fighter V: Arcade Edition (PS4), Kingdom Hearts 2.8 Remix (PS4), The Last Guardian (PS4), Shadow of the Colossus HD (PS4), Anthem (PS4), Shenmue 3 (PS4), WiLD (PS4)
