Ortlieb and Arkel (my favorite) are two top brands of panniers. My wife and I use two models of Arkels (there are many sizes and models) with narrow Tubus racks (the Tubus Fly can also attach to the brake bolt), but that rack won't work with a rack bag. There are other approaches for something above the rack with the volume of a rack bag. Make sure the P-clamps are really solid, well-mounted ones - that's where all the pannier weight transfers into the frame.