I'm relatively new to airbrushing, but when I decided to make the jump I bought 2 brushes:
1. Badger 175 Crescendo Kit
2. Aztek 470
All I can say is that the Aztek sprays Testor's Acryl acrylics great! I've really tried to like the Badger since its built so much better, but in my opinion, the Aztek wins in this match up hands down. I recently trusted a German camo scheme to the Badger and ended up respraying the whole model. Then I did it the right way with the Aztek.
The trigger travels much more and is more forgiving. Also, the dial on the body of the brush allows you to be very precise with the "sweet-spot" of the trigger. I spray with unthinned Acryl like I said with no problems so far.
One disadvantage of the Aztek is the cleaning process coupled with the plastic nozzle. Its fragile and the manufacturer recommends that you don't disassemble it, but after reading a previous post by someone here, I break it down into 3 pieces and lightly scrub it with a toothbrush to clean. No problems so far. Then I store it in a jar of rubbing alcohol to insure that no paint dries inside -- it seems to work well.
Good luck with it,