Probably the Wii U, even if we exclude BotW since it never was exclusive. Mario Kart 8, Tropical Freeze, Bayo 2 and Mario 3D World are at the absolute peak of their respective genres and there are some great gems in there like Pikmin 3, Captain Toad, NSMBU(+L) and Wonderful 101.
The Dreamcast never really impressed me since I got it after the PS2 but I'm a hardcore Shenmue fanboy. That's pretty much the only thing I ended up truly caring about in the library, even if there were games in genres I care less about.
Ignoring that the Xbox One has about zero exclusives if you have a Microsoft Windows 10 PC, I think it's very underrated. Sunset Overdrive is an absolute masterpiece of gameplay and the fixed Definitive Edition of ReCore has some of the absolute best action platforming levels of all time. Forza Horizon also became my all time favorite racing series, even if racing is less important to me than other genres. Halo, Gears and Forza have all continued to deliver great experiences too. Ori is also one of the most unique and fun metroidvania platformers out there.
So, Wii U is a small step ahead of Xbox One which is a large step ahead of the Dreamcast.