I'm a little biased because I own a company, but this also gives me a little more credibility if I'm willing to give props where props are due.
My company
Pure Performance Nutrition guarantees that NOBODY uses higher quality ingredients/raw materials (maybe equal but not better).
Gaspari Nutrition is one of the best. I've known Richie for years and know that he does not cut corners.
If I don't necessarily know the quality of a company's product, I tend to trust the ones that the information on the label is legit and the company is owned by a person that truly cares about the sport and is not just trying to make a quick buck.
I don't know Gerad Dente personally but
MHP seems to have great products from what I know.
Ergopharm has been know to have great products.
I
assume that
BSN has quality products based on what I've heard. I've never actually lab tested their products, but I've heard good things.
There are some companies I just didn't bother listing because this is not meant to be an exhaustive list.
However, there are some companies that are conspicuous by their absence
Judge for yourself.