I don't have many rulers. I use my 6" X 24" and 8.5" square ones the most. And I like my little 1" x 6" (I think that's what it is).
I have an Olfa mat and it truly is self-healing! Of course, mine is only 3 or 4 years old, but it looks great! Only when I have cut Minkee have I been able to see where I was cutting (I guess those fine little fibers get pushed into the cut, but wipe away).