Check out this link.
http://www.missing-lynx.com/reviews/...air/tamair.htm
Looks like Iwata, Tamiya and Mr. Hobby are made by the same company call BB Rich. Personally I owned 2 Tamiya Airbrushes (HG Trigger and HG SF). Essentially they are equivalent to the Iwata HP-Plus series. Since I can get the Tamiya airbrush cheaper then the Iwata one (about $20 difference) so I went with the Tamiya one. As for Mr.Hobby airbrush, I only saw them when I was in Hong Kong and they looks similar to the Iwata Hi-Line series ($$$$).