Nintendo by far. Microsoft was fail, and Sony did ok, but meh.

Nintendo if you've been a Nintendo fan at any point in your life.

Sony if you like the PS3 titles that were already announced and a few surprises.

Microsoft if you like Kinect.

Nintendo!! why? because of games after games after games after games and 3DS. Like Iwata san said gamers is most interested on games.

Nintendo, games after games and breakthrough 3DS which will sell 100 million at end

The conference felt streamlined with no gimicky presentation like commercials or loads of talk.

Nintendo won the handheld side obviously, the 3DS looks great. Sony won the console side with twisted metal, which upstaged everything including Zelda. And biggest surprise was Gabe Newell on the sony stage. 

Nintendo. Wow. Let's see: Zelda Skyward Swords, Kirby Wii, DK Country Returns, Metroid Other M, Mario Sports Mix. And the  3DS. That won Nintendo the show (with great help from the previous titles listed). New Kid Icarus (Wow, that trailer was for the 3DS? That's AMAZING graphics!). MarioKart 3D, Paper Mario 3D, StarFox 3D, and the 3DS itself. Analog stick, no glasses 3D, 3D movies, 3D pictures, WOW! This is the best day ever!!

My sword went Skywatd during Nintendo's conference.

Haha

nintendo...obviously..i mean Zelda, DK, Kirby, Mario Sports, the 3DS and all of its support. only thing missing was Pikmin 3.

sony was second. twisted metal looks amazing, and LBP2 was pretty cool.

microsft....do i even need to say anything.....