I have had work done on my E30, E46 and E36 M3's at Amato's, Philip Thearles, and Chapparone.
My recommendation is Phil Thearle's Autowerkes! Very nice people, tons of attention to detail, worked with me for some aftermarket parts I wanted, and listened to what I wanted to have done. And when it was finished it was some of the best quality work I've had done.
Chapperone's - very cool guys that work there but quality wasn't quite as good as Philip T's....don't think they quite have that level of experience.
Amato's - rude people, shitty job, more rude people. Had E36 M3 there for front bumper repair after minor collision went to pickup car after it was "finished" and the brake duct was hanging out. A day later the Turn Signal fell out while I was driving down road and scratched up side of car. I take car back and they say it fell out because the car had wrong bracket holding the bumper on from previous repair - I was like "I just paid you $3,000 to fix whatever is wrong with the front end and you didn't put the correct bracket in?" They said I didn't tell them to replace that piece! WTF they are supposed to be the expert...I told them to fix everything. They then refused to fix the scratches on the bumper that the turn signal that fell out made. DO NOT GO TO AMATO'S Autobody unless you are looking for a junkyard to throw your car in.