Haven't caught all the press conferances yet but my vote on the best thus far has to go to Nintendo.
Granted, Nintendo actually had a new piece of hardware to show off, unlike the others, but the Wii U does cover the gap between the Wii and the 360 and PS3. Needs a much larger library for launch, though, although the games already being designed for it are surprising. Batman gets a redo and the new controller makes it all worth it. ZombiU, however, is the best, and it will be able to hold its own against Resident Evil 6 and Lolipop Chainsaw.
Microsoft is attempting, once again, to do what it tried to do back in the 90's (and it failed miserably, I should add), in that they are going to turn your television into the only source of entertainment you need.
Actually, that's far from the truth. In order for it to work you need a smartphone and a 360. Basically, whatever you're playing or watching on the xbox, if you have the smartaccess app, data concerning it will appear on your smartphone.
Personally, I think it's a waste. If I want to catch info on what a particular actor starred in prior to the movie I'm watching, I simply google it.
Also, IE8 is coming to Xbox 360. My one concern about this is security. Will Microsoft be able to prevent or withstand a hacker attack or will they fail miserably as Sony did?
And, although I am happy about this I have to admit I was as surprised as anyone else, Tank Tank Tank has been voted best game of E3, beating Halo 4, which wound up in second.
I still have to catch Sony's conferance and go over a lot of games I tip my hat to Nintendo this time for learning from their previoius mistakes and getting the Wii U right the first time.