I wear a pair of "Work Safe" ones from Baileys.
They're the economy ones, which was all I could afford at the time, and I've never worn other chaps.
But I do know whether it's the lowest cost or highest end ones...you wouldn't be able to pay the co-pay for the ER never mind if you uninsured.
Over the years I've cut my jeans twice, each time in the exact same place below the knee, somehow never getting any skin. Not pushing my luck
And remember, like most safety gear...they do have a lifetime. Check the tags on them, they probably need to be washed every so often and finally replaced -- the fibers will break down and/or get gummed up with oil and dirt that slowly soaks in and they won't do their job of jamming up the saw and causing the clutch to slip and thus the chain to stop. (I don't think any chaps are rated for electric chainsaws, which lack a clutch and thus aren't as responsive to the massive jam of fibers cutting through chaps cause.)