Wii U. PS4 has way too many indies.

Contrary to popular belief, Mobile is actually one of the worst markets to start in. PC and Console is better, because the most important thing when getting started as an Indie is marketting, marketting you're brand, marketting your game, marketting yourself. Doesn't matter how fun your game is if nobody knows about it.

Mobile is an Ocean, Consoles are large lakes, and while PCs might also be Oceans at the very least you can self publish or use steam or various other websites, and use Social Media to market. On Mobile, the only thing you have is the App store, and there is no way a new game from an unknown indie is gonna stand out from the thousands of other things in that Mobile Ocean.

Smartphones then vita then x1 or ps4 then wii u

Not possible with current MS policies. its either smartphones + vita + x1 + ps4 + wii u all at the same time, or Just xb1 and nothing else, or smartphones then vita, then ps4, and then wii u and not x1 until MS changes their policies.

If you insist on "console" then the PS4 or maybe the xb360 are your best bet (mind you the PS3 had some nice titles)...

However as you noted in your answers, the PC is the definite king, not only are they cheaper on it, they often come first and many amazing titles are completely free (see locomalito's Malbita Castilla & Hydorah) some of the best indies I have ever played! Beyond this, the Humble Bundle sales makes the PC the place to be for indies.... which is a double edged sword, since there is no curation at all quality is all over the place, so my option is a new console (PS4) + a decent PC + many many old consoles...

Mind you, for the the Ouya is not bad, as you will see things that are unavailable anywhere else.

Vita's good too, but it still takes more work to get going.

The reason Wii U is so great is because they have a special setup to just make registering and getting started so easy. I'm on mobile but in a sec I can find you the link.

Make it cross play with PS4+Vita, and all the cool people also make it cross buy.

PC then Sony/MS then Nintendo

Depends on what type of game you want to make. It's probably a good idea to start out targeting a platform that doesn't restrict releases tho. Even tho the consoles have become much more open to indie devs you still need to get dev kits and go through cert to release games on them. Unless you get picked up by one of their indie publishing programs that can be expensive. Better to target PC and/or the mobile platforms first. And then go for a console port.

Well I would guess the PS4 since it has good terms for indies, plus market share.