I am told that Adidas athletic masks are good for long use in high heat, by a UPS driving friend. EShakti also has very good ratings for fit, comfort, and quality.

I like the Octagon with the filter slot lined up with the pleat. The trick is to make them to measure, being careful to match angles and lengths for nose, tip of nose to chin with mouth open, and under chin. I can wear it with a Filti liner for about 4 hours pretty well.