I'll echo the Ortliebs advocacy. My rollbacks look brand new after about five years of daily riding. They are definitely worth the higher initial investment.
This winter, the male ends of the top closure each cracked, about a month apart. I think it must have been the extreme cold we had for a couple weeks. Ortlieb sent replacements fairly promptly, but until they arrived, I substituted the ends of the shoulder straps, which I never use.
High capacity, tough, very simple to use, mount and remove.
I previously had Axiom bags, but they weren't waterproof, and they faded and got soft and saggy after a few years.