The best pollution mask could actually be any number of masks as long as they have a rating of N99 or better if you can find one (the higher the number the better). In many countries like India and China where the mask concept is well-known, the standard is PM 2.5 and that relates to the size of the particles. In North America among many other places, the idea of a pollution mask has not really caught on as much as it should (and will eventually).
Considering the wildfires that are blazing in California at the moment, it really is a good idea to forego vanity for your personal health and well-being. That being said there are some manufacturers who are trying to make masks as stylish as possible without going to the full-on hazmat gas mask.
One Company I like is the Cambridge Mask Company
Price at Amazon: $30.00
The masks not only filter particles but gases (VOCs) as well. And that is important for wildfires as it is for traffic pollution as it is the perfect portable addition to your bugout bag. Cambridge is a reputable company with excellent quality and my personal choice, but there are others who might serve as well that cost less or suit your personal style like the Muryobao Mask
Price at Amazon: $19.00
So surf around and let me know what your personal picks are. Just make sure that whatever you find has the numbers N99 and PM 2.5 or better, and that the testing has been verified.