What's the best and most comfortable full face mask?

Using ResMed Air Sense 10 Auto. Max pressure needed never goes above 8 or 9 and it varies. I want to get one and see how it is compared to the P10 nasal mask. Pretty sure I'm a mouth breather and don't want to tape lips.

I believe the most popular one is the ResMed F20. I tried it, and just could not put up with it. I need more pressure, but not much more, and I just could not get it to seal. It was very aggravating and I just could not sleep with it. I guess if I was forced to try another one, it would probably be the Respironics DreamWear Full Face mask. However, I have not tried it.

Another option may be to use a Breathewear Halo chin strap. I tried various chin straps and this one was the best. It serves two purposes. One is to keep your mouth closed during sleep, and the other is that it will keep the P10 straps in place during sleep. It is probably more comfortable than a full face mask.

Pulling this from the Mask Primer How to manage Mouth Breathing, not in any particular order.

Tongue Trick. Place the tongue on the roof of the mouth, Practice during the daytime. The idea is to train the tongue that this is a good place to be, not overnight, but it works for some.

Cervical Collar. A "soft" Cervical Collar (Releaf is popular). This helps support and align the neck and keeps the jaw/mouth from dropping. This is becoming a very popular option. Rarely used prior to mid 2016. Users are posting a high success rate with this device. When OA tends to occur in clusters at different times of night. It's an indication that an obstruction may have occurred when the chin tucks towards the chest. It's common, and the solution is either an ergonomic pillow or soft cervical collar that prevents the neck and head from being out of alignment and cutting off the airway, but they can be comfortable, prevent leaks and prevent an airway from closing up due to tucking your chin to chest and other issues. An Anti-Snoring collar, which has a small strap in back (Dr. Dakota is popular)

It's a very small investment that has worked very well for some people. More pressure may solve the obstruction, or it might go away with positional therapy.

Chin Strap. A chin strap is to manage mouth leaks from a variety of causes. Most result from the jaw-dropping or opening either partially or wider. The chin strap is to gently keep the jaw closed. If you have to crank it shut to make it work this is not the correct solution. Note that your jaw is strong enough to open if it wants to. There is one chinstrap that is notably different than others, the Ultimate Chinstrap, Search for it if you desire.

Ergonomic Pillow or CPAP Pillow, The purpose is to maintain a proper head and neck alignment while allowing for the mask maintaining the seal in multiple positions.

Mouth Guard The concept here is a closed mouth guard to keep the air from leaking out.

Taping. Definitely the most controversial. The purpose of taping is to seal the lips and prevent mouth leaks/mouth breathing. It is not to stop the mouth from opening. I make sure that I can easily open my mouth when taped, if I need to.

FFM – Full Face Mask or Hybrid Mask. This is a very traditional solution and it is generally effective.

I've tried the cervical collar already. Worst thing I've ever worn. It made me uncomfortable all night long.

I don't think there is an answer for this. Every person is different especially in facial structure. That's one of the worst parts of CPAP use, finding the mask that works best for you. Often insurance companies limit the number they let you try and it gets expensive paying out of pocket. I started out with nasal pillows, went to nasal mask and now have a full-face mask but went through several before finding the one I like best.