Which insulation is best for rodent control?

Rodent control isn't the number one job of insulation, but it's still important. Let's address the elephant in the room, your insulation won't kill mice. The way we measure rodent intrusion is if rodents will eat it readily.

Let's start with foam products. Foam products, whether its open cell, closed cell, or rigid foam, are pretty susceptible to rodents. I have seen lots of foam that was messed up badly by rodents.

Then we have fiberglass. Fiberglass, whether its batts or blown in, is very susceptible to rodent intrusion. In fact I have seen animal barns that had fiberglass (emphasis on HAD). For some reason those boogers love to have glass fibers in their throats.

Cellulose is very good with rodents. Cellulose is treated with a borate that not only makes it fireproof but also makes it very unattractive to mice from a meal standpoint. It's kind of weird the even though it's shredded paper, rodents don't like it.

Lastly we have mineral wool. Rodents won't eat it, full stop. That's all I have to say about that.