I felt N64 was a the bigger disaster because at least they didn’t alienate anyone important with the Wii U (EA? That’s about it). But unlike the Wii U, the N64 was not intended to be a stopgap console. N64’s cartridges ended up being, IMO, the biggest mistake Nintendo ever made (Virtual Boy was inconsequential in the long run so it doesn’t really count). The Wii U felt more like a break from Wii-Mania, the N64 felt more like a devastating blow to the brand that had some permanence to it.
That said, there are many more N64 games I enjoyed over Wii U. Even if I were to rank Xenoblade Chronicles X above every N64 game, N64 still wins. Mario Kart 8 is phenomenal on Switch due to the portability and multiplayer, but it felt wasted and unimportant on the Wii U hardware (much like many other games).
N64 had GE007, Mario Kart 64, Banjo Kazooie, Ocarina of Time, Majora’s Mask, Conner, DKR, and so on. These were all cutting edge greats. Meanwhile, the Wii U had a lot of outdated feeling games and games that felt like they would be better on other hardware (as the Switch proved true in multiple cases).
N64 by a landslide. Though both consoles were not my favourite of the generation: During the Wii U era I liked both iOS and 3DS more, during the N64 era I liked PSX more, and Dreamcast more at the end of the gen. I think I even liked the SNES more than the N64... I probably played Wii games 5-10X as much as I did during the Wii U era if you take away Xenoblade Chronicles X.
I describe myself as a little dose of toxic masculinity.