bgavin wrote: How does one make an intelligent choice from all this?
Just buy one. Tools are like anything else. By-and-large anything in a certain price point will all be similar. People like to shoot down Craftsman, but I've been using one of their $90 guns for well over 10 years with no problems. And trust me when I say the number of brads it's driven building BF cabs is a fraction of the number of brads that've been through it.
If all you're going to do with it is build cabs, you can save some $ by getting one that has a narrower range of lengths. Mine does from 5/8" - 2-1/4". I rarely shoot 2-1/4", but I have. They actually come in handy when attaching the top and bottom extensions to a DR before mounting the back.
But whether you end up with Porter Cable, Bosch, DeWalt, Craftsman, Stanley, or whoever, just get the best one you can afford with the features you want and you'll be fine. Don't overlook Rigid either, they have an excellent warranty.
One thing, a compact unit can come in very handy. Sometimes you'll want to drive a brad and a larger framed gun won't fit inside the area.