After having been a groomer for several years, I've seen a lot of coat variations on breeds. I've always had a soft spot for Fluffies (the long haired corgis) since i have a soft spot for the breed anyway.

I think the long-haired mastif is a type of mastif called a Tibetan Mastif. I've groomed a couple of them. HUGE mastifs, usually a tan/brown with black markings, and long hair. They kinda look like a Tibetan Spaniel enlarged BIG TIME! Great dogs tho. The one giant I did on a regular basis I totally fell in love with.