Hands down the Steamdeck. The switch is kind of a novelty compared to what it can do, unless you ONLY want to play some Mario and Zelda games. Even then, you still can on the SD.

The game I have the most hours with on the SD is 'The Binding of Isaac Complete Edition". It’s just always a bit different each play through, and the weapons and stuff are so much fun. Seems simple but very in depth and tons of unlockables.