I'm definitely back with my PC after a brief flirtation with my 360. Whole multitude of reasons:
PC is 'better' - long current console generation means even a modestly priced PC can spank any console.
Steam - Only service that actually delivered on it's promise of a 'digital-dividend'. Getting hold of a new game easy and usually cheap. Steam sales are a frenzy of gluttony for anything I've ever vaguely been interested in. Consoles whilst able, have been gutted by desire to keep publishers happy (I don't think it's possibly to download anything on my Vita that isn't £10 more expensive than buying the physical game from Amazon). Unlike many people (or at least vocal people), I'm fine with the killing of the 2nd hand game market - I just want to get something back in return.
Back to the subject, I think the WiiU is dead in the water - the people who Ninty brought into gaming with the Wii are now feasting on their ipad games. Whilst back-porting a touch-screen to a console will probably be 'compatible' with these users, I fail to see how this is going to get them to bin the ipad that they own.
PS4 - I dunno, just seems more of the same with a few bolted on software features - "share to youtube!"... oh ffs. Play a game as it downloads! (I can do this anyway, and I suspect I'm not going to be buying any digital games from you, see above).
Xbox One I think has a chance - and for some of the features it's being bashed for. I feel the TV component is going to be the seller for a couple of reasons. Most of us have a laptop/tablet/phone to hand as we watch, and I refuse to believe anybody out there hasn't scrabbled to see "what else was that guy in?". Additionally, rather than being a host for video clients, this Xbox seems to have it baked in deeper. I can easily see when you upgrade your cable subscription, you'll be offered a basic box, a Tivo or a XBOne. As happens in the mobile market, there'll be the contract and the physical client (which 'only costs a few dollars a month') - ffs they could even chuck a discounted family gold account in, along with your movie package.
Oh - and something that's been touched in is the fact what you see is a VM running - one for the game, and one for your TV. With my thinking hat on, this is ideally designed to allow what I mentioned above. The 'Game' VM is identical for all users and upgraded by MS - the 'Media' side can be customized for your cable operator.
Just realized I've wandered completely off-topic - but I guess it's mainly when I look (or even think about) the Wii-U, I'm not sure where it fits in - WHO is the target market?