Sling bag, shoulder bag, backpack, rolling bag, belt packs,.... ?
Walk around use, all day use, hiking, traveling, event shooting,...?
What is your budget? Friend of mine bought a rolling bag that can also be a backpack and cost him $450.
I find that I can never have too many camera bags. There isnt 1 bag that does it all. I have one for everyday use, one for hiking and travelling, one to carry all my gear for an event.
My every day bag is the one that gets the most abuse. It is a shoulder bag, but it doesnt look like a camera bag. Its the Lowepro Classified 160 AW
http://products.lowepro.com/product/Classified-160%20AW,2121.htm
It is a deep bag with 2 long seperators for 3 areas. In one area, I can drop in my 70-200 2.8 IS, with the hood off. That gives you an idea of depth. I mount a 28-75 to my 7D and put it in the middle area, with my 10-22 or flash in the third area. It gets heavy, and I rarely put all this gear in.
It looks like a messanger bag, but it opens from the top. You dont need to open the flap to get to the gear. It is quickly accessible. Under the flap is a zipper to make the bag extend a bit, a slide pocket for documents (I put a lumiquest diffuser in there) and a velcro closed pocket that can hold a flash, a charger...
It has an all weather bag built in (hence the AW in the name). My main beef is with the shoulder pad. It doesnt move along the shoulder strap. Minor issue, but no idea why they made it this way.
My hiking traveling pack is a Lowepro Primus AW.
http://products.lowepro.com/product/Primus-AW,1995,14.htm
Its a bigger bag with lots of straps and places to adjust the bag. It has a lower section for gear and an upper section for other stuff (or more photo gear! - but its unpadded). In the top section, I have put in there a pair of jeans, shirt, light sweater and a pair of shoes. In the lower section, I can put down my 70-200 2.8, 50mm on the top padded area and then the 10-22 and 28-75 in the other area. There is a side opening that you can quickly get your camera out of when swinging the bag to the front using 1 strap, similar to the fastpack series. Note that you wont be able to fit a gripped body out of this side opening. Side pocket can hold a 1 litre bottle of water. Tripod strap on the back
Shoulder straps are comfortable and adjustable. There is a waist belt and sternum strap. The bag opens from the BACK. So when in a crowd, people cant open zippers. You have to rest the back on its front on the ground to get to the gear (if not using the side access), which is great as the back doesnt get dirty, and this is the part that goes onto your back...so your clothes stay clean.
Its AW as well.
I'm still shopping for an event bag or a bag that can hold 2 bodies, 4-5 lenses, 2 flashes. Debating between Think Tank products, more Lowepro (Computrekker backpack),...
EDIT: and no, I dont work for Lowepro. I just like their gear and their service. Coming back from Australia, I lost the strap for my Primus that holds the tripod to the bag. I was temporarily using a velcro thing. My local shop told me to contact Lowepro for a replacement. I called, asked where I can buy one. Within 4 days, I had one Fedexed to my house, free of charge. Great service, which is key for any company to keep my business