I like the one with a thermostat. They seem to regulate the temp better.

I use one with a thermostat works well for me I do grafts in mine the winter

great!! Thanks, I ordered a large-ish mat, with a thermostat. I'm kind of worried about possibility of fire, so thinking of putting mat on cement board.

Amazon had a few reviews of mats with burn spots where it appears to have smoldered.

Is that a concern?

Have mine sitting in a tray. tray catches water run off. Which I can sop up. Remember we water a little to a lot less depending on inside moisture and temps. If you have to use an extension cord don't use a thin cheap one. They can get warm too.