Id say N64 because Mario 64 ( Ground breaking ), OOT ( Up there as one of the greatest games of all time ) and Mario 64 is my favourite Mario Kart.
I remember buying Smash as an Import and we all had a sleep over to play it in black and white lol. Classic Nostalgia
But gameplay wise future Smash games were better and I love Mario Sunshine more Than Mario 64 but 64 was awesome.
GameCube for me. It had most of the big 3D Zelda games to a capacity (wind waker, twilight princess, OoT + Master Quest. AND the Zelda collection which had OoT, Majoras Mask, a demo for Windwaker and Zelda I and II).
Double Dash to this day is a very under-appreciated history of Mario kart and Melee was the best smash bros up until Ultimate.
Mario Sunshine was ok, not my favorite but it was ok. But for Mario we also got paper Mario the 1000 year door, luigi’s mansion and Mario party 4 (the last GOOD Mario party)
after that it’s kind of a tie between switch and n64. The n64 if not for nostalgia but OoT/MM and SM64 defined the start of the 3D era. The switch however has become what I consider the culmination of Nintendo’s best.