Top speed is an interesting subject, since it depends on many things, such as altitude. The fastest aircraft at low altitude (sea level) may not be the fastest at 50,000 feet!
Of the current US Military aircraft, the fastest at sea level is the F-16C Block 50, at 810 Knots or Mach 1.3 (redline for the airframe, there's still lots of power to go faster). Up at 50,000 feet, the title goes to the F-15C, at well over Mach 2.5. In another category, at 50,000 feet without afterburners, the F-22 can go faster than Mach 1.7 (over Mach 2.0 with them), the first such aircraft to "supercruise" or fly supersonic without using its fuel gulping afterburners.
By the way, the now-retired SR-71 "Blackbird" could cruise at 90,000 feet or more and reach speeds above Mach 3!
Mike Carter, Lt Col, USAF (ret)