In a continually updated article, Upload VR has the latest information on AR and VR presence at the E3 conference later this year.
The folks at Upload VR have reached out to as many names in AR and VR as they can to get all the info they can on who's got a booth, who's showing demos, who's bringing new hardware, etc. A lot of the companies are playing cards close to their chest, so there's some speculation. One thing is confirmed, however; neither Oculus or HTC are having a booth for their respective platforms, though they will still have a presence there.
For more information, go read the article:
E3 2017: Everything You Need To Know About VR And AR At This Year’s Show.