Ortlieb or Vaude Pannier

The problem I've found with the Ortlieb is that they are fiddly and a bugger to carry off the bike when fully laden. The lack of an external pocket is also a huge pain. I've been quite happy with Cordura for rucksacks so preferred that to the Ortlieb plastic. There is an argument in favour of having breathable rather than waterproof material as anything left inside a waterproof bag will ferment if moisture can't get out which was another reason for cordura.

Ortliebs efinitely not comfy when fully laden although if you are fully laden, one would imagine that walking will not be a massive distance.
Lack of external pocket isn't really a problem for me as I have the ones with the built in internal pocket for small stuff. Anything else fiddly or small is tools and that just stays in my tool bag and easy to retrieve. I have come across people who have added velcro on internal pockets. Not a major problem.
I cycled across Canada with my Ortliebs and with a lot of rain on the way, especially on the prairies. Moisture was never a problem, partly because I was carful about what went in there but also because I was careful to air the bags out. Breathable is OK, but I think I would far rather fully waterproof and manage what is in the bag than risk water coming in from having the bags on damp ground, overwhelmed in a deluge or caught by a large splash. Breathability also tends to require something to encourage water across a membrane. Of course this is a matter of personal preference.