Based on my brief review:
Microsoft didn't do much to impress, but at least the stuff they showed was fine. Rise of Tomb Raider was solid enough, Forza 6 was a big step up from Forza 5, Rare Replay was a great compilation. Fable Legends was cancelled, and the things announced weren't that interesting compared to some presentations, but it paid out.
Sony was generally declared the winner of E3, but I'm not impressed by their relative delivery since June. The Last Guardian still lacks a solid date beyond "2016," FF7's Remake has a TBA date and apparently is episodic, Uncharted 4 and No Man's Sky have yet to be released, and it's too early to tell for Shenmue 3. It wasn't a bad year for the PS4, but the E3 didn't deliver.
Nintendo did not win. Super Mario Maker worked out fairly well, but the rest of Holiday 2015 fell flat. Star Fox Zero got delayed, Mario Tennis and Amiibo Festival were duds, and Tokyo Mirage Sessions doesn't look like it'll make many waves. And on the 3DS, Happy Home Designer did well, but Yokai Watch never caught on, Triforce Heroes is arguably the worst received Zelda Nintendo ever made, Paper Jam is the least liked M&L game, and Federation Force still has no love.
I'd say that in retrospect, Microsoft and Sony tied with scores of "meh" while Nintendo gets a "bleh."
And to briefly cover 3rd parties:
Bethesda did alright, with Fallout 4 being a hit and their other stuff not disappointing.Ubisoft did alright, seeing how The Division was a big hit and Assassin's Creed: Syndicate was a big step up from Unity. Square Enix made lots of people excited about their games again, which is still ongoing.
EA did badly. On the bright side, Madden 16 stepped up from Madden 15, a new Mass Effect was announced, . Need for Speed 2015 disappointed, Star Wars Battlefront disappointed, NHL is still not as well loved as it was last gen, and NBA Live still has little reason to exist, and I already forgot that Unravel existed.
