None are profitable. Last year Sony "wrote off" PS Vita and PS Vita TV from its earnings. Wii U is also in same boat.

I guess Wii U because nintendo did alot money with the games.

Games like Mario Kart 8 (+Dlcs), Mario 3d Wörld, Nintendoland and co are not incredible expensive to made (the nintendo studios are very small compared to other big AAA blockbusters) and sold ALOT units.
Sony sold almost no software on vita (most was third party where sony just get some licensing money, but the most money will go to the publishers)

Do you mean which one lost "less money"? Then I have no idea. Both are commercial failure.

We'll be able to tell when their lifespans come to an end.

Although right now I would have to say Wii U...?

I'm pretty sure Nintendo started to make profit of the Wii U at his second year, don't quote me on that I don't remember very well they also said that if they cut the price of the Wii U again, then it would start to sell at a loss, again don't quote me on that.

WiiU is the more profitable thanks to the good sales of the first party games, Nintendo earn more money for games than for anything else, and they are having good software numbers on WiiU.

Vita, half its games sales are digital. U will never sale enough to erase and make worth its development its weird hardware make up and costs of Hd gaming.

I have no idea about profits but the Wii U seems to have damaged the brand I guess. But then most people who have a Vita or Wii U seem happy with them.

If we go by what was more profitable my guess would be Wii U. If we go by "success" I'd have to say Vita wins that cripple fight. The drop from PSP to Vita (80m > 12m) while terrible is less terrible than the Wii to Wii U drop (100m > 10M). Also the Vita utterly destroys the Wii U when it come to number of releases so from a gamers perspective I have much more to play.

I think it's fair to say WiiU SW is doing a damn good job holding Nintendo over for the time being.

Even without 3rd party, WiiU SW aggregates not far behind X1.

Vita SW pretty much only sells in Japan. I doubt Sony gets as much royalties on Vita releases as Nintendo does on their games.