There are arguments for and against Ortlieb panniers so I bought a pair of Ortlieb Classics and a pair Arkels at the same time. I have used and abused my Ortliebs and barely touched the Arkels.

I also have the Arkel briefcase and have used it extensively but lately prefer to put my laptop in a pannier as my briefcase collects weight. I typically carry my bike tools, tube, lunch, and clothes in one pannier, but when I pack my computer I fold it in my pants and carry it on the other side for the sake of my wheel and rack.

If I were looking for panniers today, I'd look first at the Ortlieb Plus series.