I had both the fixed 10 hawke tac 30 and the adjustable mag one, the dof to my eyes was better on the fixed 10. But even better still on the panorama. 4-12x40.
I now have a pair of panoramas. I really like them.
I did have a bushnell elite firefly Scope which had an unusually long dof but the reticule wasn't ideal.
It can get very scientific why and how.but it's well over my head.
So I can't even pretend to know why they vary so much.
simple options to look through as many scopes as possible.