Showing my Nintendo bias, but the Wii U and Gamecube for me in that order.
For all its problems, the Wii U had far and away the best library of the 3 new systems in 2014. This would change drastically in 2015, but 2014 proved to me that a console's games have surprisingly little to do with its sales numbers in the modern world. If people were buying consoles for their games in 2014 then the PS4 wouldn't have started selling well until the following year and the Wii U would have sold far better that year. Mario Kart 8 alone should have sold a bazillion Wii Us. Momentum and PR mattered much more than games at this point. I think the Switch has played this out. Breath of the Wild was important at launch, but the console itself being appealing was more important, and the system has gotten so many 3rd-party games because it sold so well, rather than the system selling so well because it had these games. Mario Kart 8 has sold so well because it's on the Switch, rather than the Switch selling so well because it has Matio Kart 8.
The Gamecube selling so poorly is also pretty surprising. It was a serious powerhouse and very cheap compared to the competition. Rogue Leader was a mind-blowing showcase for the system at launch and still looks good over 20 years later. Melee was an early killer app that caused e to get the system as a kid. It had plenty of great mature games like Metroid Prime, Eternal Darkness, and RE4. It got much more 3rd party support than the N64 did. On paper it solved all of the N64's problems while maintaining the N64s strengths and should have sold much better than the N64. In hindsight it was too late to get back the gamers Nintendo lost to Sony in the 5th gen by fixing the problems with the N64, and the fans who stuck with Nintendo were less impressed with rushed games like Mario Sunshine and the perceived kiddy aesthetic of Wind Waker than they had been with the N64 versions while the Gamecube's mature games proved to be more niche than GTA and Halo were. Plus it couldn't play DVDs.







