Any of the name brands, will work now the only thing is the type and style. As at some point you will have to replace one or more of them. from the abuse the smaller one get in use.
There are the folders, assorted sizes good for carrying around in pocket or tool pouch/box
Short arm
Longer reach short arm
Ball driver type, so you can get in at the funny angles. These come in the L style, cushion grip, and T handle in both the long and short reach.
Then you have the same thing in the standard hex head as the ball driver.
Now double it when you consider that you also have metric, in all the same styles and types as the ball drivers.
You also can find them mounted into socket wrench heads to fit the 1/4"3/8" 1/2" 3/4" ratchet wrenches.
Eklind, and Bondhus along with Allen brand names. Allen is the company that invented them and as so many things became generic. I have about 18 different sets of the metric and fractional ones. Not counting the extras of the ones that are used/abused the most.
The hardened ones can break, or they can wear the corners off them then you have to dress them.
I have found that they are the tools that seem to grow in number in boxes and drawers. I have started putting all the orphan short arm L wrenches in one box, when I find them and have to change to larger boxes.
The biggest thing is to get the type and style that you will use, on your equipment. There is nothing more frustrating than not having the correct arm length to remove that hex head set screw.
That is were the T handle and cushion grip handles come in handy. As it always seems the smallest deepest hide set screws require the most force to break loose.
Here is only a sample of what is available, And they have great selections at most of the big box stores.
http://hand-tools.hardwarestore.com/22-413-allen-wrench-sets.aspx I have not used this outfit, but they seem to be one of the 800 pound internet gorilla's
