Since the OP seems to have made his decision, I'll put my Ortliebs whinge here.
The mounts are a right pain. Wonderfully easy to lift the pannier off, but forget about it if you have a rack with narrow rails - those spacers Ortlieb provide are classic pingfuckits which will just vanish when you're not looking. And then the things rattle like the waking dead.
You can't even secure the spacers properly. I've tried all sorts of glue, but they're worse than British WWII POWs. They'll find some way to escape when you're not looking.
When I was touring, I resorted to toestraps and cable ties and electrical tape to dampen the rattling, none of which was especially effective.
Replacement mounts for narrow rails would be ideal.
Carradice panniers have their quirks as well, but at least they have a more analogue system of mounting which is more adaptable. And they don't have a hook where you want to lay your head if you're using a pannier as a pillow. Also, the outside pocket is incredibly useful.
And cotton duck has a more homely feel than the plasticky mass-produced stuff Ortlieb use. Ok, that's probably not your main concern, but whichever way you go, you're stuck with 'em for a while, so the look and feel is something you'll be living with for a while, given the lifespan of your average Ortlieb or Carradice.
I'm open to offers on a pair of Ortlieb front rollers in black, by the way.