Simms used to be my favorite brand, no more. Their customer service has gone downhill, and their warranty is a joke. I bought my wife and I two pairs of G4's, within a couple weeks we both had leaks at the waist along the seams. Sent them back, they "found" other leaks that we never knew about but not the ones in the waist. Went fishing and they still leaked, took them to the local fly shop who confirmed the leaks. Simms called me and told me they couldn't find leaks and didn't know what my problem was. Basically the problem was that I paid $1,000 for bum waders, attitude and a non existent warranty.
Companies that are doing well, on both product and service, are Dan Bailey, Filson and Patagonia. Patagonia probably has the best and fastest repair/ replacement program. Orvis is great as well so long as you can get to an Orvis store. Online or phone service is good but not as good as walk in.