I did mention cotton/poly/spandex blends as more durable--and comfortable--alternatives to 100% cotton. Wool? It has a long history in cycling, particularly in jerseys--I use merino regularly there--where it's not subjected to constant abrasion (legs/ass on saddle) that'll kill it. Wool has great properties but again durability isn't one of them. You'll notice that it's often blended with nylon, partially for that reason. Other factors such as cost, reaction to moisture, dyes, sweat, abrasion, etc must also be considered too, so it's not all about durability.

To reiterate, there's nothing wrong with riding in 100% natural cotton, wool, linen, or what-have-you. Just that, commuting regularly in such clothing will prematurely wear it out. I have ten year old Levis that if worn to commute by bike (40 km round trip) wouldn't have lasted a year.

Some natural clothing products may last marginally longer than others but they will succumb earlier than their synthetic counterparts, as nylon and poly have been deliberately engineered in the lab to be more durable.

The key here is not so much the brand, i.e., Levis or Wrangler, but in knowing the nature of the textiles used. And the nature of natural fibres is that they rank well below synthetics in durability.

I have the heattech "jeans" from uniqlo. They are a blend of cotton and synthetic and pretty elastic, while keeping the jeans look. I don't expect them to last decades but they are decently cheap - and will last some years even with daily use.