I'm pretty sure VGX gets more viewers. First off, VGX is not limited to just one fanbase (ie: how many Sony/MS fans are watching the Nintendo E3 event?), second, the E3 press conferences (at least Nintendo's) are always in the morning on a weekday.
VGX is in prime time television in the evening when people are off work/school. I don't think there's much of a contest actually.