I've got a domke F-5xb and I couldn't love it more for street shooting. I leave the camera over my shoulder and the bag holds three lenses on my other side, across my body. It's perfectly-sized for three SLR lenses. The only lens I can't fit is my 80-200 f/2.8. It's just barely not deep enough to fit.

If I need something to carry more gear, I have a Crumpler 6 Million Dollar Home. It fits anything I'd need for a serious outing while still not getting in my way.

And then if I really need to lug some stuff out somewhere and use it as a sort of "mobile base," I have a CaseLogic photo backpack. I can lug tons of kit around in it, but it's more of a "take it to your location and stay there" sort of thing. I'll often load it up in my trunk if I'm driving somewhere so I know I have everything.

All of them work, but the Domke is my favorite because it's so weightless and fast to get in and out of.