I hate Ortlieb panniers. I've been leading group tours a lot and I've seen lot's of problems with them. First of all they're waterproof. Yest, that's a problem. Anything moist will stay so when you transport it in your Ortliebs. That leads to people transporting a lot of gunk on top of their panniers/racks to avoid this. Gunk which constantly has to be re-fastened.
Secondly, they tend to hop off, I allways carry a few spare straps and bungees when I'm leading a tour. THere's allways someone whose Ortliebs jump off and endanger other riders (and the owner himself).
Thirdly, they have no compartments, endless rumagging annoying other riders.
I use a combination of old Carradice panniers at the front and adapted Bach panniers at the back. If having to buy a new set, I probably would go for Vaude or check if one of the lesser known firms has a good offer.
This is the set-up I prefer for full blown touring: