Most working pros I know also recommend Think Tank. These folks have tried everything and know what works.

But I'm not a working pro so I'm satisfied with my LowePro, Domke and Beseler bags. I hate backpacks, wouldn't use one. But if you're a serious wildlife photographer and need to carry long lenses you don't have much choice. I do mostly casual candid snaps, street and documentary photography, so I rarely carry anything longer than a 105/2.5 AI Nikkor.

My current bicycling camera bag is an Agu Qyoto 820 KF handlebar bag with KlickFix adapter. Snagged it for $20 during a recent half price sale. I needed a rain resistant bag and Agu makes bags for the Netherlands market so hopefully it'll do.

All the other weatherproof bike bags were roll tops, not handy for quick access. The Agu is a canteen bag with a semi-rigid body and lid that opens away from the rider while seated. The lid is retained by a pair of elastic straps that hook across a couple of studs. It's designed almost exactly like my 20 year old Beseler canteen bag, right down to accepting the padded compartments from my old Beseler bag. It's just modified for bike use. Perfect for my needs -- assuming it really turns out to be weatherproof. We'll see this week since we're expecting rain.