No best in my opinion, I've seen several types in use and they all do the basic same thing. Not to say I haven't seen bad quality, I would say the cheap stuff online sheds more fiberglass than the higher quality kinds. I picked up a "titanium" roll from autozone, it had a nice bright silver color to it and cost me 25bucks, but I was able to take it off my muffler after a couple months and reuse it with minimal fiber loss. The cheap stuff doesn't seem to handle being used more than once very well and no matter how much I soaked it and tried rinsing it just sheds so much glass and my hands get horribly itchy. The autozone stuff I was able to use bare handed without getting itchy except for the tiniest bit.
The difference in heat is probably negligeble since we are talking about 1 inch pipes and not 4 or 6 three inch headers under a hood. I know that my fancy 25 dollar a roll prevents burns just as well as the cheap 7 dollar roll did.
A friend has some on his muffler and used standard black nylon zip ties, which I was certain would melt. But I was wrong and it provides enough protection to prevent them from melting, and that was the cheap stuff.