Ask HN: Which game console will be the easiest to develop for?
All major game consoles and Ouya.
I would bet for firefoxOS on the mobile/tablet market (http://www.mozilla.org/en-US/firefox/partners/)- just because "low-end" devices will grab a lot of market share in "developing" countries and users with their first smartphone (think about growth).
For living room & sofa consoles... the hardest part is not programming, but publishing. Try the one with more "indie" games.
Xbox has XNA, which is OK.
Ouya has many Android game libraries, amongst others: libGDX.
Or you could count Steambox as a console, and develop in whatever you want (to a certain degree).