There's alot of good dubs out there, more so then what most sub elitist would have you believe. That being said there are plenty of dubs that are TERRIBLE, but there are many that range from tolerable, to acceptable, to great. I watch alot of dubs, and even prefer them in most instances, but I have no problems with watching subs either. There are some who get hardcore nitpicky about accuracy of translation, and if that's you're thing then that's okay, but for me the most important thing is the STORY, and I'll go with whichever one, sub or dub, that I feel like best suits the story and the most enjoyable viewing experience. I feel like most of the sub elitists operate off of this older mentality from the late 80s and early 90s when the environment of the anime industry in the west was very different and the vast majority of dubs then were less than acceptable quality.
Overall I would say that the quality of English dubs peaked at around 2007-ish. That was around the time of Red Garden and Le Chevalier D'Eon (ADV) and Ergo Proxy (Funimation) and even The Melancholy of Haruhi Suzumiya and the movie (Bandai), all of which had fantastic dubs; I'd even go as far as saying that Ergo Proxy has one of the best dubs ever.
ADV started out really rough because they were owned and operated by fans; a love of anime and any slightest bit of experience with protools and you're in. It wasn't until Macek came in and showed them how dubs are really supposed to be done that the quality of their dubs went way up.
Overall, considering the entire span of the companies, I'd say that Bandai had the overall highest quality dubs.
The stuff that Funimation is doing now is okay-ish, the problem is that they have to push them out way too fast and they keep using the same VAs WAY too frequently.