To be honest, I don't think any of them "won". If anyone won, it's us gamers, because no matter what your taste, there's going to be something on the Wii/DS, PS3/PSP or 360 to suit everyone.
Personally my favourite announcements have been, in no particular order, and ignoring whether they were known before E3 or not:
-Monkey Island Remake + Monkey Island Episodic Series;
-New Super Mario Bros. Wii;
-Wii Sports Resort;
-Metroid: Other M Wii;
-Mario & Luigi 3, Golden Sun DS both are exciting;
-Microsoft Summer of Arcade XBLA list - Holy crap, between Shadow Complex, TMNT: Turtles in Time remake, Monkey Island..great stuff;
-Castlevania: Lord of Shadows (360/PS3);
-Castlevania: Bloodlines Remake for PSP.
I'm sure there's others I'm forgetting. No matter what, as I said, the gamers win, because no matter what you like, there's definitely something for you out there this year.
Edit: If I had to rank the conferences, I'd say that Sony definitely had the most glitz. They showed off a shit ton of games, including some new IP. Very cool, and good for them. Microsoft was next on the glitz level, but fails a little for not showing enough gameplay. Coming to the table with a bunch of pre-rendered videos is lame. Nintendo's conference, as usual, wasn't particularly interesting in the way it was presented. They need to learn how to glam it up a little. The motion technology from both Microsoft and Sony is interesting. Too bad it will take so long to get to market, but when it gets there it will be interesting to see if the so called "hardcore" crowds behind the 360/PS3 will even bite. The vitality sensor from Nintendo is a bit of a WTF? If they built some sort of survival/horror game that changed dynamically with your level of fear, that'd be kind of wild. I'm really curious as to what their intended use for it is.