Kane's rock, mainly because you can wet them, clean them, drop them, kick them w/o damage. Plus they are insulated on the bottom, meaning they don't waste energy heating what is under them. They have more mass, which means the heat spreads out along the surface nicely with no uneven hot spots.
But, you need to know some things. First off, they are around 1/2" thick or so, but where the cord enters they are 1" thick. You need to leave room for the cord entry to the back of the cage. This assumes the heater is inside the cage. So if your cage is 18" deep, the 18" heat pad won't fit (you'll need like 20-21" deep in the cage minimum.)
If you are using the heater under the cage, then the opposite is true.. you'll lose 2-3" of heater space in order to butt (ha ha I said butt) the heater up to the cage bottom (avoiding the cord entry), so you get like 15" of heater depth on an 18" heat pad. No big deal, but FYI.
So, in summary, they are great. Make sure your cage is larger than the dimensions of the heat pad by at least 3" depth and whatever in length. Remember that they aren't flexible or sticky, which means you don't bond them to the bottom of the cage (although silicon may work for this.) Because they are a 1/2" thick you'll need to prop the cage up on spacers to slide the heater under the cage.