I guess I'll play devils advocate here. I suspect you've narrowed your chioces down to these three and your on the verge of making a purchase. Well, this is how I would rank them. I would rank them according to function, quality, user-friendliness, maintainence, and lastly, performance. The following is sure to stir grumbling from all, so be easy on me guys...this is all MHO.
1. Badger 150
(The DO-IT-ALL work horse!)
Badger's long-standing, highly versital double-action airbrush. Very high quality, with spraying characteristics similar to the Iwata, if not identical. More versital than the Iwata, it's siphon design can spray larger amounts of paint for longer periods of time (depending on how large your project). Also, one can change out the neddle and nozzles to suite your needs (fine , Med. Large). Reasonably easy to clean and maintain, with available parts and assesories available at your local hobby shop that are very inexpensive! This great, high quality airbrush will spray everything from acrylics to laquers with ease. The most value for the money!
2. Iwata HP-CS
(Highest quality, and performance out of the box!)
For modeling, this is a superior quality airbrush that will satify your need for detail as well as general spraying. The Cadillac of the three, and the extra $ is worth every penny! Smooth trigger action, gravity-feed color-cup- this is widely regarded as one of the most easiest airbrushes to use and maintain. It's .35mm nozzle is forgiving with most thicker viscosity hobby enamels and acrylics, and sprays them equaly well, be it fine lines or broad areas. Top of the line!
3.Omni 4000
(Same great Badger quality, Iwata performane only more affordable!)
Another High-quality airbrush, now manufactuered by Badger. Remarkably similar sprayg characterisics to that of the Iwata. It's unique reversagard tip alows you to get closer to your subject, facilitating great fine-line spraying and tip cleaning. Quality construction, user-friendly and easy to maintain, with parts readily available at very reasonable prices, far less than the Iwatas. Same easy of cleaning like the gravity-feed Iwata but, without the extra cost.
Pipe in guys if I'm missing anything...
Greg Williams
Owner/ Manager
Modern Hobbies LLC
Indianapolis, IN.
IPMS #44084