Sony looks to have the best showing so far. Their system has similar games to Xbox One, but with slightly better specs, better (in my opinion) exclusives and NO DRM! NO ONLINE REQUIREMENTS! That one was a real kick in the teeth to Microsoft when they announced that, I was floored.
A lot of people have predicted doom and gloom for Wii U based on slow initial sales, but I'm not worried. It's sold more during the same period after launch than the PS3, and the PS3 is fine despite its own slow start. The 3DS was also considered dead in the water after its launch, as well. The sales will pick up after more good exclusives are released and perhaps after a price drop. as is what happened with both PS3 and 3DS. The latest Nintendo Direct showed off some really impressive, fun looking games. So I'm quite happy with the system so far, even if it did start slow.
Microsoft let slip that there would be some kind of system for preventing or limiting used game sales on Xbox One, this made people mad. When they finally laid out their detailed plans, it made people furious. Renting games for Xbox One is impossible, buying and selling a disc used would be limited to games that the publisher decides can be bought/sold. You couldn't even GIVE someone one of your games unless they had been on your friends list for a minimum of 30 days, even then that game could never be gifted ever again.
The system would HAVE to go online once every 24 hours to authenticate all your games, or they'd stop working completely. If you brought your games to a friends house or another system, that check in time would be once every single hour.
When Sony announced that the PS4 would have none of this, it was a real kick in the teeth to Microsoft. In my opinion, if Microsoft doesn't do away with their plans for these requirements and restrictions, they're in real trouble.
Oh, and the PS4 is $400, unlike $500 for Xbox One.