I own stuff from Arkel and stuff from Ortleib. Both are deserving of their top quality reputation. The differences between the two brands are clear.
Arkel appeals to those who like lots of compartments--a place for everything and everything in its place.
Ortleib appeals to those who like the flexibility of big empty space with no pesky dividers cluttering things up.
I decided on a pair of Ortlieb Front Roller Classics. I do like the fact that the GT-18 has external pockets, which come in handy as I can just throw my keys, wallet and cellphone in there without opening the pannier itself. However, the Front Roller's form factor (12.5 L x 2) was more appealing to me than that of the GT-18 (18 L x 1). The pair configuration allows me to go lightweight by using just one when I don't have much to carry. My wife and I can use one each on a weekend bike trip as well.
