For a begginner, I'd recommend the Paasche H. It's easy to use, reliable, and very capable. Most modeling needs are be easily met by it. Until you become a skilled air-brush artist (lots of practice and experience), any needs beyond what the H could deliver would probably be beyond your skillset even with a high end airbrush.
The Badger 200 also is an excellent brush. I mostly recommend the Paasche H over it mostly on the basis of price. The Paasche H set has everything you need, aside form the compressor, while with the Badger 200, you need to get a good hose and color cup separately, so the total price for the Badger is significantly higher.
Based on my own experience, with double-action vs. single-action, I'm of the minority opinion that it is a benefit to start out with a single action AB like the Paasche H or Badger 200, rather than trying to jump in directly to a double action unit.
However, in the double action action world, I recommend against Aztek. I don't think that that they have any cleaning advantages over any other AB, and they seem prone to breakdowns. Although a lot of people like them and even swear by them, a lot of others, like myself, had an Aztek die for no apparent reason. I followed all Aztek cleaning and usage instructions, but after a very short service life, I had to mail it in for warranty replacement.