Call me a heretic but I always preferred the Soviet/Russian doctrines of aircraft design, and not only in looks. U.S. fighter jets have (had?) the best performance money can buy, but the sacrifice was in practicality. Take out our runways and we have very few aircraft with short-field capability, much less aircraft capable of operating from grass or natural-material strips, or imperfect surface streets. In general, the landing gear of U.S. aircraft isn't sturdy enough and the tires fitted are relatively small and highly pressurized. We also don't make a habit of having intake filters or screens. Though these problems could be ameliorated fairly easily, it would take a crisis to catalyze. Would it be too late then?
The Russians still operated aircraft with vacuum-tube electronics well after silicon chips became common, because they're easier to work on in the field. Rugged landing gear, large, low-pressure tires, intake screens...and much lower costs per airframe. I can't help but think their doctrines would work out better in a slugfest between world powers. I doubt the PAK-FA will be as rugged as their usual fare, of course, but the SU-27 line has been fantastically versatile and doesn't really need replacing so much as supplementing.