That is a question that is asked quite often in the P&M section. There are some factors that come into play when looking at an airbrush.
How much detail are you wanting to do?
What is your price range?
What are your personal preferences?
What environment will you be using it in? (house, garage, man cave, ect.)This is mainly for the compressor.
Two things that have been agreed on in most of the threads is dual action and gravity feed are the way to go and use a compressor that has a tank. From there it is up to you.
The popular brands are Badger, Iwata, and Paasche.
I would recommend going to a
LGS and hold a few to see which one feels good and you can start from there.
I use a Paasche Talon and I absolutely love it. I do base coating but have started to work on my detail work with it.
http://www.chicagoairbrushsupply.com/nepatatgsetw.html