I'm tempted to put Switch in first place because its concept brought me back into gaming after years that I'd been playing only a few games (mostly PC strategy games) every once in a while. A hybrid home-portable console is what I didn't know I needed, as I can play it a lot more than I could if it was just a home console ("no time to play on a TV screen" is exactly the reason I never bought a Wii U or PS4 and still have a huge backlog of PS3 games I rarely get the time to play) - and it's not just portable but being able to play games that have the scope of home console titles while in portability. And, of course, it has loads of great games, making the previous point even more relevant.
Second (or joint first?) place goes to the Gamecube, which I can say is the console that got me into Nintendo games in the first place (I had had a GBA, but Pokémon was the only Nintendo franchise I played on it before; the only other consoles I had played on were the PS1 and PS2). Pokémon was actually my gateway into the Nintendo universe, as the games that made me want a GC were Colosseum and XD, and then I discovered all the other franchises as well (the GC I had came bundled with MK:DD, then I also bought Melee after that). It's partially nostalgia and partially because the GC catalogue is full of gems (with F-Zero GX being the main reason last year after moving home I connected my GC to an old TV).
Honorable mentions go to the DS and Wii, which were the Nintendo consoles I spent the most time on - they get a somewhat mixed reputation due to the casual games and shovelware, but had some really high-quality gems too. But I've always been very happy with all Nintendo consoles I had, so that could apply to all of them...