NGP'll be the big attraction, since that's when they'll really info-dump for the thing and put together a more definitive lineup (much like how Nintendo had their conference back in January to do that for the 3DS, whereas E3 was more about unveiling the thing itself)
That alone should secure them the E3 victory this year. The only thing that tops a new handheld is a new console, so unless Nintendo (or, less likely still, Microsoft) drops a new console, Sony's got this year in the bag, which, by my reckoning, will be their first win since 07 (and 07 was barely a win for them, all of the big three were weak that year, Sony was just trying harder to please)
Monster Hunter: pissing me off since 2010.