Mobile consoles like PSP(\s*)? and Nintendo .?DS.? are loosing quickly market share to AppStore-based devices (from apple, google, etc...) in mobile or tablet form.<p>I would bet for firefoxOS on the mobile/tablet market (<a href="http://www.mozilla.org/en-US/firefox/partners/)-" rel="nofollow">http://www.mozilla.org/en-US/firefox/partners/)-</a> just because "low-end" devices will grab a lot of market share in "developing" countries and users with their first smartphone (think about growth).<p>For living room & sofa consoles... the hardest part is not programming, but publishing. Try the one with more "indie" games.
Depends what languages you know etc.<p>Xbox has XNA, which is OK.<p>Ouya has many Android game libraries, amongst others: libGDX.<p>Or you could count Steambox as a console, and develop in whatever you want (to a certain degree).