given my caveats above, I agree with Aurthur, Chopard LUC under Mr. K-F Sheufele, cares very very much about customer satisfaction and SAV, though how this translates to the field varies quite a bit.
This personal "care" is one of the reasons he and Chopard LUC won the first PuristSPro Purity Prize 2009 click here
I would add AP USA - I know a few people who have had some problems (which service center or brand hasn't?) but for me they are batting 1000 (sometimes after a round of make good... ) I had experience or followed first hand in 8 markets plus HQ; the only one where I consistently heard about problems was Germany and UK - consistently heard problems but don't draw any conclusions, I am not surprised I didn't hear about no problem cases!
Richard Mille (again, it sometimes takes a round or two more than I would like, but given the highly technical and sometime just post-prototype level of complication of some of the pieces as well as the relatively smaller production scale, I don't find that so surprising or objectionable, kinda like I expect Ferrari and Lamborghini to need more work and care than Porsche.) RM USA and RM HQ try their best, is all I can say.
Patek USA in the past, but in the past year or two...
No personal experience with Cartier but anecdotally I've heard only good things.
GG and DR globally (I had experience or followed first hand in 4 markets plus HQ) when they were independent and under Mr. Gerald Roden was fantastic, waiting and seeing under Bulgari.
Blancpain globally because Mr. Marc Hayek cares, but regional experiences have been spotty and inconsistent until escalation. BP USA through their NYC boutique has been great, and Marc Junod cares, though actual work in the workshops can be a little unpredictable, but I know regional and HQ care so I can live with it.
GP USA used to be handled by RGM (and still are, I think) and were good. GP HQ was good though slow. I've had mixed experiences with GP HQ - some of the best if I had to get specific individuals involved, some frustrating probably due to a bad day and unlucky draw on who I got (this was several years ago)
The independents are a crap shoot, and you really are at the mercy of the head independent in the workshop as well as their mood, workload, and financial condition. But at least you don't have to go through "layers"
Svend Andersen - great service, but occasional a come back or two
Paul Gerber - one of the truly great watchmakers and truly nice human beings in this, or any other industry (finishing style may not be everyone's cup of tea)
UN - I want to say good things about them, because I know they do great work and have some great infrastructure and logistics in place to help ensure things go right and smoothly, but since I know some of their executives do not appreciate and take badly even legitimate reporting of negative experiences (with no intention of bashing whatsoever, just bringing things to their attention) I refuse to make positive comments either.
Hey, wait, I just did...
Vacheron - has varied over the years, and I personally know about mostly good experiences, but I also know about some dubious experiences. With Mr. Proellochs I knew I had recourse; with Mr. Torres, I have no idea since he doesn't care about me or ThePuristS or PuristSPro.
Jaquet Droz -
oops, gotta go...