Without meaning to pick an argument with mumbojumbo, I think it's fair to say that his opinion is very much in the minority re Jantzen's quality (although it does often take people until their second Jantzen order to get the fit right, which is why you should always start with a single-shirt order with either Jantzen or Baron). The real issue with Janzten is they are swamped with orders and are terrible about responsiveness and customer service, so there's really no saying when your shirts will arrive. Most of us who use them are happy enough with the end product that we're willing to put up with that, but it definitely is a hassle and not the way to go if you're in a hurry.
I know Jovan has used Baron Boutique, so he may be able to comment on them. I have ordered two shirts from them as an experiment. Both are fine, although a step down in quality from Jantzen, at least as far as the fabric (construction seems solid in my non-expert opinion). I prefer most to most mass-produced OTR dress shirts you'll find in department stores and the like, because the custom fit is so much better (especially given the price). The positives of BB as opposed to Jantzen is that they're organized, responsive, courteous, and quick (I think each shirt arrived in about 2 weeks, certainly no more than three, with good email communication along the way.)
Anyway, if you're inclined to check them out, they're at jantzentailor.com and baronboutique.com. As I think I mentioned, if you search the forum you'll find many threads discussing the various pros and cons of Jantzen in particular, which a number of people here use.