Roll-top bags dominate the world of commuter backpacks as they offer better water-resistance compared to bags with zips. Because no one wants to arrive at work with soggy clothes to change into.

I want a top-loader but can't decide between two Deuter bags, the Aircontact 75+10 or 65+10. The 75 might be a bit big for city travel, but it could carry all my climbing gear, trekking boots ...