Not counting PC since that is easy mode, I would probably say the Wii for me personally. I have had: n64, gc, gameboy (pocket, color, and advance), DS, and ps2 besides the Wii. But I think I put more hours on the Wii than any of those. Super Mario Galaxy, Metroid Prime Trilogy, Zelda Twilight Princess, smash bros, and mario kart wii. Very solid catalogue. Plus it had the virtual console and was what allowed me to play some old classics like Super Metroid and Donkey Kong Country 2. I never had a snes growing up so that was pretty huge to me. I even cut my teeth on some FPS games like call of duty, world at war and conduit lol.
The Wii might be cheating a bit too since a lot of my fondness for it does come from its backwards compatibility with the Gamecube, and gamecube games were still very relavent during that time. Metroid Prime 1 and 2, part of the Trilogy of course. Smash bros melee. I even had the Zelda collectors edition disc which had GC ports of zelda OOT and MM.
So yeah Wii was definitely kind of cheating since in some ways in my nostalgia I mix it up with basically every Nintendo system that came before it heh. But even on its own it had a solid lineup IMO.