I think Bick and Don have hit the most important issue spot on, it's less about the airbrush, than it is the requirements of the user. The AB's I have come to favor for finest detail work are the badger 100G, Paasche VJR and Iwata M1, all with the finer needles and tips. Really, the differences between them are rather insignificant, the major issue is the distance from trigger to tip, shorter is best for me.
Don loaned me his Sotar once, as well as it worked I felt a bit uncomfortable with taking care of it, those tiny bits are very easy to damage or lose, and really expensive if replacement is needed. Those that favor the Sotar love them. They can do some really fine work, I guess it comes down to what do you really need and what will work best for you, on a routine basis.
I recommend buying no more airbrush than you will actually use and feel at home with. When I say my VJR or 100G works as well for me as the Sotar, it's not about the AB's, it's about how well I can use them. No need for a Ferrari, if I'm only going to Safeway.
Patrick