I am a strong 'half-stop partisan.' Anecdotally, I think knives with half-stops are much more likely to last many years with strong snap. Many if not all of my very old cam-tang knives have floppy blades, and I don't have a square tang knife with bad snap. Again, all anecdotal evidence: I know there are exceptions, like my grandpa's old Camillus, which shows that a well-maintained knife will last no matter what. But it's enough to make me pass up some patterns that don't have half-stops, and seek out others specifically for that reason. E.g. for reasons of pocket carry I prefer a round-bolstered stockman, but I will choose a square-bolstered Case 6332 because it is one of the rare stockman patterns with half-stops.
This could be due to the more evenly distributed wear on the tang/backspring junction rather than at one concentrated point. I also like the 'self-cleaning' joint function evident especially in a flush square tang like a GEC trapper or the original Remingtons. It also just feels very satisfying when a blade thwacks into place in all three positions. De gustibus...