I didn't know how much I would love the rack track sliding thing until I got it. I LOVE it. Velcro isn't that difficult, but the QR is really, really nice. When I commute or run errands with it, I just slide it off, throw it over my shoulder with the shoulder strap, and I'm off. I don't think you can go wrong with Topeak- lots of different models. I would like to upgrade to the one that pinkbikes has with the drop down panniers- so I can cram more stuff in.

I think the Axiom bag looks great, too. Might just be whatever one you think looks "sexier" on your bike.