Out of all the camera bags I have either used or considered- none were comfortable and functional together. To hope for a the one bag you find to be stylish as well would be flat out impossible. Most companies try and sell a camera bag as a box with shoulder straps on it. Camera bags are designed by camera people, when what you really need is one designed by backpack people. Solution: Put together your own camera bag.
Pick your pack according to your lifestyle. My daily routine includes a bike commute in an urban environment, usually some walking and being prepared for rain. I have to carry around a bike lock and cable, bike lights, some spare tools, a rain jacket and fender just in case. All that in addition to any photo equipment I might need for the day requires a specific kind of bag.
I chose a cycling backpack that has a quick access zipper on the side; the TLevel Inifinity Rolltop 43L. It has adjustable hip and chest straps as well as load lifters, which I can't do without. It has multiple compressor straps to minimize the bag size and there is a back pad frame to put some space between your back and the bag which minimizes sweat. TLevel's come in a bunch of awesome colors and has reflective strips on them for riding at night.
As far as a camera bag goes, it doesn't cut it. So you'll need a camera insert. The Crumpler Large Haven portable padded protector is what I use to store my camera and lenses inside. There are a bunch of brands that make inserts. Crumpler happens to be camera bag brand that made a color scheme close to what my backpack was. The Large Haven is enough to fit a Nikon D800 with a 24-70mm zoom and a flash with some room to spare. It also has pockets along the front for batteries, cards, and film. The TLevel can actually hold two of these bags easy—though I’ve only needed one.
There are different means to an end, but the way to choose a bag and insert is the same for everyone; Start with a bag that functions in the way you most like and the insert that works for your equipment. A made to order camera bag beats any out there on the shelf.