Pardon me for stating the obvious, but hows about one that fits?

Apply mask to face WITHOUT strap. Breathe in through nose, sucking mask onto
face. Now hold your breath, static - NEITHER in NOR out.

If the mask falls off, no good. If the mask stays on, fine.

Having found one that fits, I prefer a mask with a single piece of glass
rather than the goggle-mask, which has a piece of glass for each eye. I find
the bar in the middle intrusive, and if the mask is applied at an angle to
the face I see double.

Having found one that fits, an inexpensive mask is every bit as good as an
expensive one. All you need is a flat piece of glass (or whatever) to keep
an air pocket in front of your eyes so they work as they were designed.

Ken

I'm happy with that same mask. Just the luck of the face, probably.

Try using it with the strap looser and/or tighter, and in varying
positions on the back of your head. If that doesn't prevent the leak,
you're probably out of luck with that mask.

Here's my theory: that particular mask has a wide, soft skirt and I'll
guess, on your face, that skirt is right over a sharply defined facial
crease made deeper by the widening of your mouth by the mouthpiece,
possibly worse on the right, if your regulator pulls in that direction.
Check how the mask fits with a regulator in your mouth.

snip

As some astute poster once said regarding mustache mask fit, look for a
mask with a narrower, firmer skirt, at least in the area where it makes
contact with the problem area, in your case, your mouth creases
perhaps.

Although, a leak over a mustache isn't the issue here, preventing the
lifting of the skirt over a facial crease is similar. The narrow, firm
skirt will mold the face to the skirt a bit more than a wide, soft
skirt.

Also, for a difficult to fit face, I think it's important to check the
fit of the mask with the strap on and with varied amounts of strap
tension,  and with a mouthpiece in your mouth. Maybe even while pulling
the mouthpiece to one side, like a hose might sometimes do. Turn your
head side to side; that changes facial contours, too.

You might need a buddy to assist you.

While doing all that, rather than sucking in so hard that you pull the
mask into hands-free position, VERY gently blow out and then VERY
gently suck in just a small amount of air. Try to judge if any air
moves under the skirt anywhere, and how easily it moves.

Note that using too much pressure or vacuum will be meaningless.

Also, look in a mirror while you do this and try to see where the skirt
might lift up. Once you see the problem area, it will be easier to
judge the effect of various adjustments or movements.

Good luck!

HTH.

--
Dave C