Heh, this is no contest. N64.
Ocarina of Time gives the N64 an auto-win against any other console, and Mario 64 makes the victory that much sweeter, but even if I'd disregard those the N64 still wins. To this day, my N64 collection is still the biggest collection of all the consoles I have and nearly all of them are classics. 'Proven' classics even.
No other console has had so many classic games, or so many that still stand out in my memory after all these years. No, it wasn't the first console I've ever played, but it's memorability definitely makes it my favorite. Unlikely to ever be surpassed.
For the life of me I cannot understand why it's sales are disappointing, I guess there is truth in the CD/cartridge story even though gameplay-wise I personally also preferred cartridges.
Have to give the XBox one plus though: It did have Knights of the Old Republic. I was jealous at my cousin for a time. He had the XBox and I didn't, but due to circumstances it was at my house for over half a year, so I did play the console enough to know. Of course he had KotOR before that and I had to get in on PC instead.
Still, one of the best games ever made does not win to like ten of the best games ever made.