I have a UWS that came with the truck when I bought it. I like it a lot, better than some of the other brands that I have seen. It is a good size, not too deep into the bed and not to tall over the bed rails. One thing though the locks are kind of chintzy, you have to jiggle the key to get it to lock and unlock sometimes. But it doesn't bother me too much.
I got the black one from Tractor Supply. It may seem like it will sit too high but it doesn't block any of your vision when looking out the back window. (at least not on my '03) One thing however...because it's aluminum, it racked a little bit in the bed of the truck after about 2-3 weeks. Now you have to push the lid toward the front of the truck and then down to get it to close correctly. I cannot simply push it down to get it to latch. Next tool box I get for a truck will be steel and I will not mind paying the $600 or so for it. I've heard the UWS' are better at preventing this 'racking' so that there is no worries on it not closing correctly. Probably because they use a thicker gauge construction. (more money however)
I've had a UWS aluminum box for about two and a half years now, and I have had zero problems with it. It still closes well and has remained watertight. I apply a little white grease to the latch pins when I think about it, and other than cleaning it out periodically, I've done nothing else to it. Like one other poster said, the key wants to be stubborn sometimes, but a little jiggle takes care of that.
Unless you're set on black, like I was at first, think about the temperatures where you live. I was talked out of a black one by the fact that the aluminum will keep the contents a little cooler in summer. I carry WD-40 and various other pressurized cans in there, and I didn't feel like creating IEDs out of them in the heat of summer when I didn't have to... Anyway, mine cost about $270 or so, but I had it delivered by a friend. I have been very pleased as I have seen some around that don't hold up nearly as well.
The United Welding Service box is the best for the money. It has a double walled lid that is foam filled. Most outhers have braces welded across the lids. Since the only thing that ever goes wrong with a box is that it will not close properly, lid constuction is the important factor. They have them in low pro or regular, about the same price, as well as many outher styles. Black is more expensive since they take a finished box and powder coat it. They are made in Perry Fl.