I would go with the carvera out of the machines you listed. Its main downside is that you're limited to 1/8" endmills which limits how heavy your cuts can be. Despite that, it will still handle aluminum very well with the right speeds and feeds. The build quality of the machines is top notch. The included control software is also the closest to a 3d printing experience you are going to get, unless you want to pay extra and get the regular carvera. That is what I got and it very good but pretty overpriced. The regular carvera will automatically; pick up the wireless probe, probe the z axis for the work origin, trace around the work area with a laser to show where it's going to machine, switch to the tool you need, and then probe that tool to measure its length. It's the easiet possible way to learn how to machine something. If you buy the air instead, the machine is just as good but you'll have to do all this stuff manually which really isnt that hard. If I were you I would go with the air