I will echo others that fit is the most important factor. The fit procedure described above is a good one and one that will serve you well. In my opinion, cost is the absolute least important factor, as others have said.
The second factor to consider once you have identified a good fit is low volume (Atomic Frameless) vs. high volume (Mares Esa). Volume refers mainly to the area of air between the mask and your face. The real bottom line here is that high volume masks tend to sit farther from your face. They tend to let in light and have many windows for high-visibility. Lower volume masks tend to sit closer to your face and some prefer them for their lower profile and increased viewing angles.
I have used both and initially preferred a higher volume mask for its ability to let in light, among other things. That said, I once tried an Atomic Frameless mask (a very low volume model) at a Disney Dive Quest dive (great experience, by the way) and immediately went out and bought one. I have been so pleased that I have never used another mask since. That said, my preferences might not be your preferences
If you can, dive some different masks and see what you prefer before you buy. After you buy, do yourself a favor and rinse your mask after each dive (it may reduce the yellowing associated with clear masks) and will help to preserve the straps and any metal pins or connectors by minimizing exposure to salt. You also will prolong the life of your mask by saving and using the case your mask came in. A mask in a case is much less subject to damage and will likely last longer than one that sits loose with your other gear.
Good luck with your choice and Happy Diving!
Mike
