Do you want waterproof with no or minimal pockets? Or coated nylon fabric (claimed to be waterproof, it isn't) with more pockets?
Ortlieb is the gold standard for waterproof panniers. Occasionally REI has a good sale price on them once or twice a year. Sierra Trading post occasionally has a limited selection on a good price. My Ortliebs are a bit over 10 years old, they have made some tweaks during the past decade, but as far as I can tell no changes were negative. Mine are the Front Roller and Back Roller. I think the Front Roller name may have changed. I also have the 31 liter Rack Pack. The roller type panniers (the non-City version) have a strap that goes over the top, I use that strap on my front ones to hold my rain gear where it is handy.
Carradry are another option for waterproof. I had back luck with their front ones, but Happy Feet on this forum has bought some since then and he was very happy so perhaps I just got a bad pair. I also have their rear ones. The rear ones had some sewn through seams that leaked on my first trip, I have since seam sealed the seams.
There are many other waterproof brands that I have not tried but others like.
Non-waterproof, I have some Axioms that I got at a garage sale, worked fine for a five week tour but the coated nylon is not waterproof and the seams were not sealed. But I did not expect them to be waterproof so anything I had in them could get wet without impairing my trip. I also have some 10 year old Nashbar ones that I have not found a reason to use them, used them for a tour over a decade ago and they were good enough that I still have them around.
Lots of other non-water proof ones. And some come with rain covers or a rain cover is available for them.
Most of my tours have been with the Ortliebs, but my last tour I tried my rear Carradry and Axioms on the front, not because there was anything wrong with the Ortliebs, but because I had them and decided to try them out. The Ortliebs are better built, more waterproof, slightly heavier, and slightly smaller than the combination of rear Carradry and front Axiom. In the future I will bring the ones that I think will work best for a particular trip, I expect to use both in the future.
First photo, Ortliebs. The 31 liter Rack Pack on top of the rear panniers. Their straps are designed so that you can clip the Rack Pack directly to the non-City version of the Back Rollers.
Second photo, rear Carradry and front Axiom.
ADDENDUM ADDED HOURS LATER:
In the second photo, on top of the dry bag on my rear rack is a black and yellow mesh bag that I sometimes use for damp clothing or laundry that has not dried out yet. That is one problem with waterproof panniers, especially the ones that are almost air tight, you do not want to have damp stuff in them on hot sunny days. I find that damp stuff on top like that does not dry out while I am riding, but it does not get moldy either.