Interesting.
An issue with which I'm not only unfamiliar, but which I've never even considered.
A quick reference to the chart in the attached PDF file suggests Lyocell as the clear winner if based solely on wearing properties. But another characteristic presented is ecological impact, where it seems Cupro has an advantage.
However In my quick scan of the PDF I did not notice a few other characteristics and issues I would consider relevant. They are:
1. Price
2. Availability
3. Whether the study was controlled for differing qualities of each type. I.e., is there a range of quality within each type, and are types of equivalent quality being compared?
Studies can be a tricky thing. A good consultant can build you a study to prove the moon is made of green cheese if that's the outcome you want (And you pay enough!