Consider the cushion paddings, water resisitency, durability & reliability. Popular brands will be Lowepro, Crumpler, Tenba and some others. Of course, there is a price difference in the brands and models. Look at the B&S and you can get some idea on the popular brands. Personally, I have tried Lowepro and Crumpler and they are both very good. :thumbsup:
First comes what equipment you are gonna put in that.
Number of bodies
Number of lenses
Size of lenses
External Flash - Yes/no
Want one that can hold laptop too ?
How big a tripod do you have and do you want to sling it to your camera bag too ?
Based on the above list, you can then choose whether you want to use Shoulder bags vs Backpacks.
Shoulder bags allow you to take the camera out and change lenses quickly. However, it does put a weight/strain on one side of the shoulder.
Backpacks distribute the weight more evenly, but you will need to take the backpack off, every time you need to access your camera.
Next comes brand
Next, do you want it waterproof or just a raincover will do.
In my opinion, Lowepro makes some good value for money bags.
For one camera, one or two lenses, Lowepro Nova 2/3 is a good choice. Its a shoulder bag.
If you want to carry a laptop as well, Lowepro Compudaypack is good. Its a backpack.
If you want a proper backpack without carrying your laptop, Lowepro MicroTrekker 100 is a good bag to start with. Or the slightly bigger version MicroTrekker 200.
If you want the convenience of a shoulder bag and the comfort of a backpack, you can try out the Lowepro Slingshot 100/200 bags.
is a good site to read reviews and photographs of most of the popular bags. the photographs are posted by real users and not by the manufacturers of these bags.
Other folks have already given you some of the other popular brands.
The best thing is to take your equipment to a shop, put everything that you will usually carry in it and test it out firsthand. Don't always necessarily buy the biggest bag that will hold all your equipment. It might end up being an overkill, unless you plan to carry all the stuff everytime you step out of the house.
Good luck in your bag search. I can tell you for sure that you won't stop at one purchase. :bsmilie:
most of wut u need to know r already mentioned in the preceeding posts. one point to note is as the amount of ur gear grows so does the collection of ur cam bags, pouches, accessories etc... i'm not askin u to buy the "biggest bag" avail to fit everything u can think of into it, just buy one which u feel tat will sufficently carry ur "most used" items, and do not be too kiasu.