I am curious about this too. I can tell you who to avoid. Do not ever go to Northeastern in King of Prussia. A lot of bad juju with them. Rush jobs will take over a month and they charge more than a dealership for sub-par service.
If you are in King of Prussia, SuperQuik is a great shop. Those guys are honest, and great guys to boot. Damon and Dennis are the guys you want to see there.
Thanks! I am not originally from the area and my old man was my mechanic growing up. Since moving out this way it has been tough to find a decent mechanic (been screwed by KOP's Northeastern and Norristown's Pep Boys). I will have to check SuperQuiK out next time I need major work done.