I like a bag that's fast to work from while hung on the shoulder, and that doesn't require dragging the equipment past zippers or through a smaller opening. I like a top flap that closes securely, but folds back completely out of the way for continual quick access. My preferred bag for the size kit you mention is an old Tenba P-series that's no longer made, but the closest current equivalents I've seen would be the Domke F-802 or F-803, both body-hugging satchel style bags with plenty of storage.
My wife and son use Crumplers (discontinued models about 3 years old) that I find are slower to work from, largely because the openings seem undersized for the interior room, and they also seem bulky and a bit clumsy for the capacity relative to the bags I prefer. The Crumplers are nicely made and well padded. Newer models may have improved access. My son will borrow one of my Tenbas if he can when he's carrying one SLR and two or three lenses.
The Billingham Hadley bags also look like a style I'd prefer, but I haven't tried them. When I see Billingham bags, my first thought is that they likely contain lightly used Leicas, and would be worth stealing, but that's just my personal prejudice.
Lee