When I started a little over 3 years ago I went through the same dilemma, I can sympathize the way you feel. I can tell you that a bottom feed brush its easy to use but cleaning takes a lot more work vise gravity feed, I own 5 airbrushes and my workhorse is the Iwata HP-BR .3mm 1/16 Oz. cup double action. I like the bottom feed with the larger tip due to you can spray heavier paints due to the larger tips, like.5mm. Now Iwata is not the only brand that works good that is many more, it's just the ones that I happened to go for. One advise I can give you is to try to understand how an airbrush works, understanding the mechanics will help you to trouble shoot problems when the airbrush start to have spraying problems. Airbrushes are very simple and will made, most of the time is operator error, ask me I know. One reason I like Iwata is because they really stand behind their products, I am sure other manufacturers do the same. Hope this helps. Big Tip REDUCE YOUR PAINT
Gino