www.lewistaylorshirts.com are top of the list for custom shirts
When in situ, I had great experiences with Jantzen. I even had them create a pattern for a 1920s shirt so that people here could order online. Rudie got one good shirt from them over t'internets using the 1920s pattern, though it shrunk in the wash … the next one was way too big in the collar. I believe he also had issues with communication.