I don't know much about the Arkel bags, except that they have a good reputation. I do have some experiece with Ortlieb Products. I have been really pleased with their performance. This is especially true when I pull my dry
camera out of the bar bag after a day of heavy rain. Their mounting system is secure and convenient to use.
I've been using Ortlieb panniers for the last 4 years. These have close to 8,000 miles of hard touring on them. They are amazingly tough. I have crashed several times (nothing serious) with the panniers taking the brunt of the fall. I have also tried to clean off high curbs with my right front pannier several times. Prior to getting the Ortliebs, we used a couple of different brands of non-waterproof panniers, and while they worked OK in most situations; the contents still got wet.
Ortliebs are really waterproof. On our last trip this summer we had rain 35 out of 90 days. Being waterproof may not seem critical until it gets really wet. It is also nice to be able to hose them down to clean the mud off. Between my wife and I we have 2 full sets, plus rack packs and handle bar bags. Besides tours she also used her small panniers for commuting to work.
Having said all this, I think any good set of panniers will do the job. Also, buying panniers is not an irreversible commitment . If they don't work, sell them and try another brand.
P.S. I also use Tubus Racks.
Last edited by Doug64; 09-22-11 at 10:50 PM.