Well, that's few criteria, but let's start with that:
Online gameplay: The very few online time I've spent in Wii U (Smash Bros.) has been quite solid. In general, I'm getting a higher quality connection than in my 360. Also great not to have to pay anything, however, for those yearly 60 bucks, you do get 24 games to download. It does annoy me to have to depend on Xbox Live Gold to access Netflix...
Prices: Yeah, the Wii U is cheaper than the Xbox One, but that has a lot to do with the hardware. Beside that point, accessories for both are fairly expensive in my opinion. I have yet to see this in the Wii U, but in my country, the Wii games I wanted to buy (Twilight Princess, Mario Galaxy, Smash Bros. Brawl, No More Heroes, etc...) never dropped in price and were often more expensive that any generic AAA title at launch on other consoles.
DLC: Yeah, the DLC in the eShop is quite expensive, but there seems to be little of it and I guess this depends more of the development studio than the platform.
As far as hardware, it's quite clear that the Xbox One (and the PS4 even more) is far beyond the Wii U's capabilities, though I feel despite a certain having passed, the new generation has yet to show us what that power can do. As of today, I haven't seen anything from the Xbox One or the PS4 to really make me marvel at the next-gen. It's just a bit more polished than the last generation and not at all impressive if you've gamed on a high-end PC in the last couple of years. So despite the very marked difference in specs, I think the difference is still not very evident in games. Anyone who feels otherwise please enlighten me with some examples.
Title availability in another relevant topic.
Not one of the 3 current-gen consoles have a very impressive roster so far. The Xbox One and PS4 have come out with very little more than the same games coming out for X360 and PS3 still, or expanded and remastered versions of other last-gen games (Tomb Raider, Sleeping Dogs, GTAV, etc...).
On the other hand Nintendo always has the advantage of their unique IPs and briefly the were catching up with games like Black Ops 2 and Splinter Cell: Conviction (which, by the way, is a grossly underrated game), but once again they have very little availability of multiplatform games. Hopefully they'll fix that front on their next console, because that's losing them tons of sales.
Sales, which were brought up, are actually very similar between the Xbox One and Wii U, from what I've seen, with Microsoft ahead by a little... the PS4 leading the way by far.
But at the end of the say, I always think if you're a dedicated gamer and you have the money, you're best off having all the consoles (and a PC!), else you're missing out on something.
