I like surprises, but often I get my hopes up and the announcement lets them down.
Here's a bunch of possibilities, many of which were probably mentioned already:
Twisted Metal
Infamous 2
Killzone 3
Resistance 3
LittleBigPlanet 2
Demon's Souls 2
Motorstorm 3
Dark Cloud 3
SOCOM 4
The Getaway
Sly Cooper 4
many of those are already confirmed, or at least as good as confirmed, so they wouldn't really be a surprise.