The traditional way of putting a mask on your face without the strap and breathing in is flawed because you can make a poorly fitting mask stay on.
A better method is to tilt your head back, put the mask on your face, put a reg/mouthpiece/snorkel in your mouth, and have someone look to see if there are any gaps and that the silicone goes around your eyebrows.
If trying to decide between two masks, I'd suggest considering which has a better angle of view, make sure you can still squeeze your nose with gloves if you wear them, and which has lower volume. If I missed anything, please chime in.
A better method is to tilt your head back, put the mask on your face, put a reg/mouthpiece/snorkel in your mouth, and have someone look to see if there are any gaps and that the silicone goes around your eyebrows.
If trying to decide between two masks, I'd suggest considering which has a better angle of view, make sure you can still squeeze your nose with gloves if you wear them, and which has lower volume. If I missed anything, please chime in.