It's an unpopular opinion, but the N64. I haven't spent nearly enough time with the Wii U, but man the N64 felt dated from a gamepad design perspective, and games were few and far between, even if it had some all-time classics on it. Looking back on it, it just felt like a wasteland most of the time. 200 games released during its lifetime were nowhere near enough IMO, especially when the PC space was booming and the PSone was drowning in games. The Wii U it had at least some true gems like Captain Toad, Bayonetta 2 and Splatoon, that came out of nowhere and surprised me, and at first, even the hardware design felt like it could have some decent ideas behind it, even if Nintendo failed to deliver on the promises.
I am a bit surprised by the hate the GC is getting? I always felt it was one of the most underrated systems ever created. And man, I loved the box shape and the fact that it was really rugged and portable
Edit: love that nobody voted the SNES thus far, that system is brilliant