Both three companies need E3, for different reasons. Sony needs to get a precise release date and update trailers decent amount of their big projects, like Shenmue III and FF VIR. Nintendo needs to show great software for this year to continue the Switch's momentum, and Microsoft really needs to show enough exclusives to show their weight. So I'd say Microsoft needs it the most, but I don't know what's their plan lately, so I don't know.
You know it deserves the GOTY.