Face coverage (more protection than anything else) seems largely to be a double-edged sword. On the one hand, this is airsoft and protection has to be one of the most important parts, but often protection comes at a cost.
I usually wore a black bear mesh mask which offers probably the best face protection available. However, I have found it's shape makes it hard to sight my rifle and it's uncomfortable as heck!
Alternatively I would wear just a shemagh because that is extremely comfortable and there are no sighting issues, but I am conscious of the safety it offers. I once got shot straight in the face with an underbarrel m203, and if I hadn't been wearing my black bear, I could have lost all my teeth.
Now, in hindsight, that was probably a once off but even normal bb shots to the face make me uneasy and I don't know if I want to take the risk. I'd appreciate any input!
(P.S. If you guys think I'm being paranoid, please tell me! When I first started airsoft I wore no face protection at all. I probably still wouldn't if my friends tooth hadn't been shot out by an ACR.)