I have the Topeak rack and bag, and a full set of Ortlieb rollers. For commuting, I greatly prefer the Topeak, which is expandable to carry lunch, and laptop and extra clothes, as needed. The Ortlieb bags have the advantage of being waterproof, whereas the Topeak bag needs a rain cover. The expandability and easy on/off feature of the Topeak bag is really nice. Also, not having a bag or two hanging off the side in the rear is nice for narrower areas, and the Topeak bag is definitely more aerodynamic, especially with the panniers folded up.