Konami is the obvious answer. After 2015, they barely count as a games company anymore.

Square-Enix would probably be second for the stupidity of their PR and strategy in the handling of the Tomb Raider deal. Reviews all point to a decent title that deserves a greater share of sales.

The clear winner is Konami for pretty much everything they did across the board this year to their own studios and staff.

Dishonourable mentions:

Nintendo would win it easily for me if Konami hadn't been around, this was the worst E3 they've ever put out, followed by multiple poor quality game launches (devils turd,fatal frame, mario tennis ultra smash, and animal crossing amiibo festival) and a buggered up translation job on Xenoblade with social justice 'enhancements'. Seeing as they're by far my favourite company, it's been a real trainwreck of a year likely caused by the death of Iwata and essentially a three to six month power vacuum leading to poor quality control and a real lack of vision. Late in the year they seem to be on the uptick again at least.

EA for their hollowed out,empty Battlefront game with it's $60 season pass.

Bethesda for refusing to hire testers and change their engine even though they're sitting on mountains of cash from Skyrim.

Don't forget that after Skyrim came ESO which they sunk an absolute ton of that cash pile into, another thing is that while I agree games should be tested, and of course Bethesda games go through tons and tons of testing before they're launched, I think a game world like Fallout 4 can't really be playtested 100%, because a dev can't really expect everything to happen which can be done in games which are so open world, I mean even with Skyrim last gen, I don't think there was 1 person who 100%'d that game without at least encountering 1 or 2 bugs... the only thing was not everyone encountered the same bugs, there was some more common than others, but no one ran into exactly the same issues in the same area's as other players, just because of the nature of the sandbox game that it is.

Don't get me wrong btw, I love a game to be fully tested on launch, but at the same time, with a player base like bethesda games has the only way to find all the bugs that they will find by bugging into every wall they can while playing... is to release the game and let the players go nuts finding the bugs in it, some people (myself included) love finding funny bugs in those type of games, it's a large portion of the fun if you ask me.

Konami of course, tough Warner Bros did a pretty shitty job too...

Konami by miles but when it comes to PC that has to go to WB easily.

Konami, no question.

When they patch the 'performance issue' by just removing the shadow altogether instead of actually optimizing (That even modders did it on first month without modding tool.) There is no excuse. None.

Bethesda would have won for me if wasn't for Konami.