I have the long Snap on, and they're great. As you note, also expensive. I just got another full set of them last week in a box I bought, and they are even nicer than the others I already had. They're 1968 vintage.
I have (and had before Snap-on) long Proto in both offset and straight configuration. Used on ebay, they're about 15 to 20% of Snap-on retail if you shop carefully. They're very close to as good, and maybe even preferable to the Snap-on. I personally really like the ones with less offset, I don't like the deep offset ones as well.
I had a set of old Craftsman, they were nice and thin, but weren't strong enough for their length. I bent some of them, and after warrantying them for ugly clunky new ones, got rid of the set. The overall quality/usability of the Craftsman isn't even a close third to the snap-on and proto. The sad thing is the sears worshipers on ebay will pay more for them than proto.
I have a few older williams long dbe, but they are shorter than the snap on and proto. I like them, but like the short proto and short snap on better; the williams are just an in-between size that is awkward. Where I really like the DBE wrenches is the super long and the short. The ones that are the same length as a combination wrench, I just use a combo wrench instead. The other place that the DBE really excell is when you put one in your pants pocket. The short ones are great for this. The box ends don't poke you in the leg when you move, like a combo wrench does.
Overall, I'd recommend the Proto as better price and equal quality to the snap-on.
PS: As an after thought, had one additional comment. I have some nice, shiny, SK ones also. The offset in them is kind of a double 90 degree jog, they sit on the bench and in the box awkwardly, and tend to twist as you use them. I really, really, really do not like them. The gradual sweep of the Williams, Snap-on and Proto is much preferable; they don't twist off when you really torque them. Craftsman also had that sweep right on their older wrenches, but they were just too weak.