Where I worked we used the thick heavy rubber mats. They worked nicely if the horses were well behaved. The thin rubber ones were almost the same price and only lasted a couple months before tearing.
Even with the thick mats we had some horses that would paw and dig and once they found an edge they used their teeth and pulled them up and all over the place and if the sawdust gets underneath the edges become easier for a playful horse to grab or for you or your horse to trip over.
I often thought the ones with the interlocking (puzzle piece or zipper type0 edges would have been better but the boss never tried those.