I used to swear by (and at) my Botch...er... Badgers. But since I got my hands on an Iwata....HOOBOY!
I've got the Eclipse, and it's a double-action. Double-actions are sometimes tough to get used to, even if you've used another d-a type before, but this was a sprayer's dream! It's also a gravity feed, so paint flow problems are a thing of the past. I took a buddy's Iwata for a test drive and just had to have it. It was so comfortable to initially get on and spray. Never had that easy a time before with a new brush.
They're more expensive than Pasche or Badger guns, but they're also more durable and hassle free. No stinkin' teflon bearings buried in the body, no maddeningly frustrating assembly/disassembly for cleaning. Not that the Badgers or Pasches are tough to take apart, the Iwata is just that much more simple. Though I admit, simplicity is a plus in Steve's Dungeon! LOL
Anyhoo, the slightly higher cost is worth it, if you're really into it and will be using it alot. Another brush that I've used and like is the Badger Sotar, or as I call it, the Zoltar airbrush. LOL HOWEVER, that's quite a bit more expensive than an Iwata Eclipse or any of the other "standards" that are out there for modelers.
The other important factor is your air supply. You can have the "greatest airbrush in the world", but if your air supply sux, it won't be worth a damn. So take that into consideration as well.
I suggest trying out a pal's, like I said, that's how I came to have the Eclipse. Plus it's just an excuse to hang out with your modelin' buds.
Fade to Black...