That is for the last 25 to 30 years; here is the collective wisdom of CrookedTimber commentators. The picks are good ones, but I’ll predict the lasting work for (if not in) political philosophy will come from some other direction entirely. How about neuroscience, experiments, or evolutionary psychology?
I’ll run a similar query soon about economics, with open comments of course. Get your thoughts ready. If you leave a comment today, restrict yourself to political philosophy.