I was disappointed with all of them.
Microsoft's was pretty boring, and they still haven't shown me any use for Kinect in what I guess has now been dubbed "core" games.
Nintendo would have blown me away with a 3DS with 2 analog sticks. But it has one. It's a flaw with the PSP and it's a flaw with the 3DS. Also, kind of a low resolution screen for my tastes. It's lower resolution than the PSP (400x240 for each eye vs 480x270), but it is a smaller screen (3.5" vs 4.3") so pixel density is likely similar (too lazy to do math right now). For the record, I think the PSP had a great screen when it was released, but it has since been eclipsed by just about every mobile device.
Sony was meh. Some cool exclusive content from third parties. But overall, kind of light on news. Twisted Metal had been heavily hinted at already, plus I'm not a big fan. InFamous 2 and Killzone 3 had already been revealed. Move? Ehhhhhhh.
I guess my vote would go to Nintendo, just for the sheer amount of new stuff they brought to the table. Sony blew their load early, and should have saved more than 1 surprise for E3. And Microsoft was just terrible.