some people argue that Sherry is better.. I've never dealt with her, and I've heard she can be abrasive in her communications, yet she has a long list of devoted customers
I've had Don at DAG do a complete CLA on my M3 with excellent results, and I'm sure there are many others on here who have cameras that Don worked on (or is currently working on).. I wouldn't hesitate for a moment to send another camera to him.. he has always responded quickly to my emails, and he did the work right on schedule.. he even patched up a chip in the vulcanite, which I didn't ask him to do since I was going to recover the camera after having him work on it
the bottom line is, you can't go wrong with either of them.. your final decision might be based on turnaround time and cost