Terry I know you know wool so whats the best if money don't matter..
That depends on what you want to use it for, how it's constructed, and what breed of sheep is being used. I have wool garrmets that will be pasted down beyond me only to be pasted down yet again.... much like a wool rug being passed now for generations....
Not much plastic , polyester and recycled sprite bottles will see such honor. Yak has its place, and has served its purpose all over the globe for eons keeping people warm but its not superior to wool.
We made a blend of alpaca and NZ wool once and found alpaca to be ready nice to work with. We only used it for its soft hand as there was a short lived trend for "soft" carpet. Durability wasn't there as our test ratings went down and we could only warranty residential and not commercial.
I've even got some some nice Llama out of Peru.
But Yak is cool, and much better than retread soda bottles.