Personally, I think the best trailer goes to Watch Dogs. It could end up being a generic stealth game, but the trailer definitely made me interested.
Metro's trailer was pretty nice as well, but live action trailers never tell much about a game. I'm looking forward to the full game. I've been wanting to play Metro 2033 for a while, but it's pretty much guaranteed that I'm not going to buy it.
Beyond has the potential to be great, so I hope they don't squander the opportunity there. Indigo Prophecy is fairly enjoyable, and I've heard Heavy Rain is excellent, so this will probably end up being good as well.
Metal Gear Rising looks like it could go either way. The trailer makes everything look so chaotic that it could end up just being a big mess. Apparently Platinum Games is developing it, so I have hope for it.
Microsoft's conference was, once again, a complete joke. The only big games that were shown are sequels to extremely popular franchises, and all of them had already been announced before. The rest of the show was taken up by features completely unrelated to gaming, and it felt like all of them were already announced last E3. The smartphone/tablet integration could be nice, but I own neither, so I'm not all that interested.
Sony's conference was slightly better, as they showed off a few games that look good. I don't own a PS3 or Vita, so I don't have much to say about any of the features announced.