FA-18 Super Hornet. It's a tried and tested design with no new infrastructure needed to sustain it. Face it, the U.S.S.R. no longer exists, and China loves our money. To continue to build our military in order to fight a non-existent "Opfor" (e.g., Soviet Russia or China) is a waste of time. Look at how war has changed, it is no longer fought on a massive scale, it is fought by small units. We didn't kill Osama Bin Laden with a tank shell, but rather the 5.56X45mm bullet of a Navy SEAL's rifle.
Also, the fundamental ideas of war have changed. Our enemy is not large or well equipped, but rather small, elusive and crafty. The need for submarines has passed, as has the need for tanks and manned air-combat fighters. The new opfor no longer has tanks, ships, large cities, or military aircraft of any kind.
-Penguin