Which manufacaturer does the best job with scope finishes. I think Swarovski/Kahles have by far the most durable finish.

US Optics SN-3 I had, had a tough finish.

If the aluminum tube is anodized there are only going to be two variations.

1. Sulfuric acid anodizing Type II
This is the anodizing found on common consumer goods. Usually very thin maybe 50 millionths to to .0001" thick.
2. Hard anodizing Type III
This is an engineering coating that is like a layer of ceramic on the surface about .002" thick. Very tough

I think the Zeiss Conquest has a very durable finish.

Swaros and Kahles have some sort of super hard anodizing...they are tougher to scratch then a Zeiss for sure . Leupolds IMHO have one of the softest anodized finishes. I am talking VX-III