Probably Microsoft. They needs a high-profile presentation to show and convince people that the xbox is still a viable platform. They need to make a splash with high-profile games, preferably exclusives.
Nintendo has lacked BIG games this year, but by no means a drought(at least in my opinion). But i don't think Nintendo is dependent on E3 to show their big games
As for Sony, if they didn't show up at E3 it wouldn't hurt them at all