Really depends how you want to use it. Personally I'm not a fan of most Kata bags due how they hold or the lack there of my gear. But I can almost say that about every camera bag out there. I have heard good words about the Bumblebee series. They seem well made (at the higher end) like most companies.
I struggle with bags non-stop. Never find one that covers all the uses I have or want to have.
Thinktank Urban Disguise 40:
Just got this bag and I'm really liking it. More professional looking, compact, and it holds a ton of gear - and I mean a ton. It has places where you can stash everything but it's design isn't restrictive to only particular items. If that makes since. Really well made as well. Wedding load: 70-200, 105vr, 50mm,85mm,SB900, D800, flash meter L-358, extra batteries, % accessories. And I could have added yet a second body and probably 1 more lens or flash. And it doesn't look like it is bulging. Quickly becoming my 2nd favorite bag. Don't like, too professional looking for casual & pulling gear over zippers.
Marmot Flathead waste pack w/ Padded single lens inserts (Domke/tamrac/etc):
Go to this over and over. It has a shoulder strap and you can tuck the waste belt into the side. hold 3 lenses (105 & 70-300vr largest size) and a couple of water bottles or lenses on the outside. I like it since if my shoulder gets sore, I can uese the waste belt to take the load off. My primary walk around pack for primes or with a wide angle and 70-300VR. I have loaded it with: 12-24, 28-70, 70-300, 35 1.8, 50 1.4, and small accessories (batteries/cloths) with my d300. I wouldn't suggest it, but it can be done.
InCase Sling Pack CL58032:
Good for light kit and for taking a small amount of gear to friends, or short walks (<5miles/8km). Body, 3 lenses, flash, couple of batteries. Nice looking, compact, well built, no-nonsense bag. Dividers are in set places so it really limits the bag.
Lowepro 35092 Primus AW:
Great long hiking pack or even weekend away pack. Distributes loads well. Never had the "side" open up at all. Bottom will hold 1 long lens, 2-3 small/medium lenses. Top section (what I love) can fit a ton of photo gear (loose) or a full change of clothes. There is an outside "open" pouch along the back that can hold easily, a coat, blanket, laptop (in a sleeve.) I have used this for many over-nighters and long day hikes with a ton of gear and it felt great. They are larger though and the waste belt can not be "tucked away" but holds the load as good as my large hiking only pack.
Lowepro Rover (CompuRover)/Lowepro DryZone Rover:
Have both, love both. DryZone is a waterproof bag and the compuRover has a computer slot (do not have that one just the older non-computer one). (Same for both;) Holds the most gear out of any bag I have had. Really deceiving from it's looks. I can fit 6 lenses (70-200 and under) in the bottom and anything I want in the top which fits even an Orbis ring flash (which I love to use)! They only thing is the sholder pads are not as good as the Primus, but still way beyond cheap packs. I mostly use the Rover to take a bunch of gear for extended weekends (non hiking) as I can get anything I want in the bag. I picked up a barley used dry zone version for winter so I can set & sit the bag in snow. That version also can have a water pouch as well.
There is something about Domke bags that just work really well. Light padding but sufficient, configurable with inserts to no end, rugged and they just work. They look like they wouldn't but I like them over any shoulder bag I have ever had. Thing I like the most - can get to gear easily, not scraping over zippers. Casual looking.
Classic bag. Outside: 2 pockets that large enough to hold a folded SB900 or small body. Two pockets under main flap: pens, batteries, cloth, flash light, narrow items. Main compartment I use a quad insert in the middle with 4 lenses (50&35 stacked) and two bodies. If I'm visiting family for an extended weekend this is what I take when I need less than a back pack but more than a small bag.
2nd most used bag. Slim and can hold DSLR with a prime or up to 105vr and two additional lenses. It has a unique bottom zip opening (with catches on the sides) that allow you to split the bag in half and get to the bottom. I create a sideways "T" divide with a long (full bag) on one side (fits 105/Sb900), split the bag in top/bottom with a dslr and prime on top (sideways) with two primes (35/50/851.8D) on the bottom. Holds about the same amount (lenses) as the InCase Sling Pack but much smaller.
Daily bag. I carry my X100 with two bottles of water, notepad, and pens most days. I have fit a D300 & Prime in it as well. Smaller than the F-xc and a bit narrower but great as a daily bag. I have carried this every day for 2-years and, I don't want to really admit it, but is a man purse for walk around/haphazard shooting.
Wow - more than I planned on writing but I guess that is how I wish others would explain their uses for bags.