I'm only interested in Bethesda, Sony, and Nintendo, but I'll probably watch Microsoft for Project Scorpio. I'm also hoping to hear something Dragon Age related from EA, but I'm not getting my hopes up.
Of course I'd like to see an Elder Scrolls VI reveal, but I feel like if that was going to happen, we'd only get a shot, 5 second teaser for it, seeing as Bethesda themselves admitted the game was a long way off.
They probably wont be revealing it this year, but if they did they would probably show more than that. They've said that they'll only be showing off games once they're ready for release (or, well...as close to ready as Bethesda thinks they are) from now on and seem to be sticking to that.
Speaking of Bethesda, I'm fully expecting some sort of Fallout 4 Ultimate Edition to be announced, if only because I was a fool and bought the season pass while it was recently on sale despite E3 being so close. At the very least I imagine they'll bring up Fallout 4 VR again, unless that's already happened and I never realized it because it's VR.
I'm not expecting much from Nintendo beyond stuff we already know about, but I'm hoping to hear something about a Dragon Quest XI localization and a Switch version reveal, or maybe a Dragon Quest Heroes I+II localization announcement. Seeing more Shin Megami Tensei Switch and maybe some of the recent 3DS games that Atlus just announced for localization would also be nice.
As for Sony, I expect ten minutes of ominous chanting before a new God of War trailer and probably more Days Gone and The Last of Us II. Beyond that, I don't really have any expectations. I'm hoping to finally get a release date for the Jak and Daxter PS2 Classics releases (and maybe a Jak 4 reveal? No? Okay...), and maybe a FFVII Remake trailer of some sort.