Ahh Mallard, I see you have met Pandora, and you have chosen to take a peek inside the box....I'm surprised there are so few responses. This is usually a question that gets pounced upon like buzzards on a carcass or flies on a pile of...well, you know what I mean. You don't mention where your confusion lies, so helping you sort through it is a nearly impossible task. All airbrushes are 'user friendly', just to varying degrees. None will compensate for lack of talent or skills; those you have to learn. Properly maintained, any airbrush will last for years. Like everyone who has ever picked up an airbrush, you will no doubt at some point buy, or at least try another. I have four, and none are the one that I can do everything with.
Have you done enough research to know what each type is, how it works, pros/cons, etc? Is there any chance you can borrow one , or find a store with a reasonable selection to see how different airbrushes feel? Any pawnshops where you might find a used one? An airbrush is a lot like a pen. We have a preference of which ones we like because of how they fit in our hand. Do you prefer fat, medium or skinny? Light or with some heft to it? Some people will argue this brand over that; for most criteria, the differences are small, and for every feature that's great on this one, another brand will have it beat in another area.
I know guys who use nothing but an external mix single action (Paasche H), which is simple to use and easy to clean. They build armor and aircraft, and can manage the squiggly camo on German planes, at least in 1/48 scale. The needles/tips change out quickly enough too, so there's not a lot of time lost there. A single action internal mix needs a little more teardown to clean, but with smaller needles and tips might give you finer lines if you need them. Some people claim the external mix has a tendency to spatter, but others argue it's never been an issue for them. The Paasche H has a bit of heft to it, which some like and some don't. Badger makes one that is similar but lighter, but I don't know the model offhand.
Double action are all internal mix, and take time to disassemble for cleaning. One upside is that you can vary the spray width as you spray just by moving the trigger back instead of having to stop and swap out needles and tips as with a single action. However...like learning to play a trombone and figuring out where the slide needs to be for a particular note, you have to practice, a lot, to figure out exactly where that trigger needs to be in its travel to get a particular spray. Add to that varying air flow by how far you push the trigger down. Learning all that takes more patience than some can muster. Don't get me wrong, a double action is great, and the only way to go, if you need what it can do. If you don't need all the capabilities, why buy them? One upside to a couple different double actions (Paasche VL and Badger 150, and maybe others) is that there is a screw adjustment you can use to make them function as a single or double action. You have the ease of use of the single, but with the potential of a double to use somewhere down the road when your skills increase, or you find a need for it.
No matter which airbrush you decide to buy, you have to practice, a lot. They all come with instructions and practice exercises. You would be wise to do them. You don't even have to waste paint, use food coloring and water, and spray on craft or poster paper.
You didn't mention whether or not you have an air supply. That is almost as big a debate as the airbrush; everyone has their preference, all for good reasons, but.... The airbrush dedicated models from Paasche, Badger and others are nice, they're quiet, they're a lot of things, including expensive (some around $400US, none less than $125). They're also useless for anything besides an airbrush. The one I currently use is a Campbell-Hausfeld 3/4hp with a 1.5 gallon tank, paid $45 for it. It works great, but it's noisy as hell, and when I move out of my house to an apartment it could present problems. I may have to go back to a nitrogen or CO2 tank setup; stone quiet, but the tank has to be refilled occasionally, and Murphy's Law says it will run dry on a Sunday when there are no welding supply stores open. Let's hope you're not even more confused than you were.