The Valve one is already out of the question imo.
Valve owns Steam and is basically the go-to for PC gaming, why on earth would they sell to anyone when they practically have no real competition in the PC space and make millions/billions off of Steam alone? Doesn't mean Microsoft couldn't try to ask if they wanted but still that seems like it would be something that Valve would never even consider, especially because of how they like to do things their own way.
EA seems more plausible because of EA Access already being on Xbox and Microsoft seemingly wanting to push Xbox Game Pass now, but I still can't see that happening unless Microsoft is truly willing to pay that much for it. Would be a huge game changer for them though, would be massive.
And as for PUBG Corp weren't there rumors that Microsoft had already tried to buy them and it didn't go through? So I dunno.
edit: added more to this to clarifyLast edited by FloatingWaffles - on 29 January 2018