QB or Pass Rusher for our 1st round pick?

Well that goes without saying if only because a top QB will play at the top of his game far longer that a top DE or OLB.  The way some of these guys are getting injured today they may have as short a career at the top as some RBs.  Watt is out for the rest of this year needing more back surgery.  Maybe he came back too fast.

The fact that for a QB it is more mental and about gaining experience is just one more reason why some tend to get far better as time passes and if they don't get too beat up career ending injuries are less frequent. IMHO you can still win more easily with a dominant defense than you can with a dominant QB though.

I also agree that those top players like a Brady or a Dent or a Bennett and others who were drafted late or not at all are outliers and have to be discarded from any significant statistical analysis.  The best will almost always be drafted early and by that I don't necessarily mean top five but many who've consistently been the best for the longest time were top five or top ten picks.  One single year of stats won't tell the whole story either because some of these guy never had double digit sacks before and never will again and some will.  Career stats are a better basis for an analysis.