In reply to ecrinscollective:
I wouldn't be too sure about the basic design meaning they are all equal. I've had a karrimor one which is ok, but the shoulder strap layout means it is crippling with even a small amount of weight in it, similarly a mountain hardware one had some swivel buckles in the wrong place causing discomfort. I've also got an Overboard one for work which again, not too bad, but when you start to fill it up it just swells like a giant balloon, which no amount of strap tightening will return to a manageable shape!
I suppose it depends what you'll use it for and personal preference etc, but I've been quite surprised how much variance I've experienced from such a basic design concept.
I do feel like you really get what you pay for with the North Face ones. One of the few bits of TNF kit that I actually like!