I'm a fan of a few companies:
Corsair - I love their cases and PSU's, although they are not the most reliable for parts.
Samsung - nice selection of quality AND reliable products. Not got a bad word to say about them.
ASUS - another company I think of providing quality products
NVIDIA/AMD - for providing great graphics cards all these years, and not taking each other out of competition.
And of companies I'm not a fan of:
Microsoft - because they're too big for their boots and ignore what people really want
Intel - for bullying AMD years ago causing them to suffer lost revenue when they had a lead
MSI - Terrible reliability, every product I've ever owned, and nearly every product that friends/neighbours have owned, that is made by MSI, has failed very early. Quality Control is awful.
Apple - For obvious reasons!
RAMBUS - Patent Troll.