That's a toughie. And honestly, it sounds as though the problem isn't so much the mask as simply general comfort. Let's start with the basics and go from there. I apologize if you've already been through this but bear with me.
The first thing you want to do is check for over all fit of the mask. Place it on your face without the strap. Inhale and hold your breath. You want it to stick for a few seconds. If you can get 5 seconds or more, it fits. After that try it again with your mouth slightly open. You're simulating having a snorkel or a reg in your mouth. The reason for this is sometimes opening your mouth a bit can increase the size of smile lines on your face or possibly curl your lip a bit breaking the seal on your mask.
If it holds still it fits. The air around you is far less dense than the water you'll be in. So if air doesn't leak in, water won't.
If you find several that fit you can take the time at this point to compare the vision out of each. Don't move your head to look around but rather hold your head steady and look about with your eyes. check your peripheral vision. Check to see if the mask frame hits your nose or does it bother you anywhere?
Once you find a mask that fits the rest is up to you, but the best thing to keep in mind is this... when you are in the water, if it isn't leaking and you can see out of it, quit worrying about it. I know that sounds really simplistic, but its amazing what taking the focus off of your gear and placing it onto your surroundings can do for getting accustomed to using scuba equipment.