Depends on your purpose.
This silicone "soldering mat" is quite useful for working on itty bitty stuff, and all the little partitions are fantastic for organizing teensy tool, parts, screws, and suchlike. It's heat resistant, which I guess is why they call it a soldering mat.
There's also rubber "sports floor" mat, the stuff they put on the floor in gyms to cushion dropped weights. The problem with this stuff is that it's somewhat porous, which may be suboptimal for leaky drippy stuff.
There's also garage flooring, more of a solid rubber stuff that's usually textured on one side and smooth on the other.
I have a roll of rubber "runner" material I use for making bench mats, and other handy things besides. You can easily buy as much or as little as you need in any home store.
Stable mats are also a great material.
I think the key here is to have a few different choices on hand depending on what you're doing. And stay alert of offcuts; with some of the flooring materials, you have to buy a large quantity, but sometimes you can score leftovers.