Joshua is a reliable guy to buy from. I have ordered at least 15 watches from him over the past year and not a single problem with delivery. (knock on wood). He is always willing to fix any problems I have had, such as a faulty movement on a CHS GMTIIc, that was turned around in less than a month, so I would highly recommend him.
All of the recommended dealers pretty much have the same inventory, so its more about their style of business than anything else. With Joshua, you get lightening fast shipping, quick communication, and quarantee that he will take care of any problems that occur.
However he is a drop-shipper, which increases your risk of getting a flawed or problem watch, and his prices are a bit higher than other dealers. IMO the QC that other dealers tout is hit or miss, and not to be taken very seriously.