Bethesda for the Creation Club and wanting a piece of money off of modder's hard work.
Valve for not making games and not taking steps into making Steam a better experience, especially in customer service.
Gearbox for Randy Pitchford's arrogance
Rockstar because of shady microtransactions
Microsoft for killing FASA and Ensemble.
EA has gotten much better with how they've improved Origin and the shakeup to Battlefield, but they still haven't atoned for the sin of killing Westwood
But the worst company right now, above everyone else, is Ubisoft. Churning out shitty HD remasters like the Heroes of Might and Magic 3 one while completely destroying any sort of chance that a great competitive game like For Honor could've gotten had it not been for its P2P networking and its psuedo P2W microtransactions where you needed gear that boosted your revenge mode. Just a terrible company.