i personally love the ultratherms, thats what I started with. they have a thicker laminate on them and look neater. but once you start getting more snakes, the cost is well.. costly lol. i use flex for the racks now that I have more snakes but put the ultratherm mats to good use, they're in my incubator.

they claim you can use the ultratherms w/o a t-stat, I never took that chance. I always used a thermostat with mine.