The most used russian fighter aircraft and The most used U.S. fighter aircraft.
The most widely used Russian fighter aircraft historically is the Mikoyan-Gurevich MiG-21.
Introduction: The MiG-21, nicknamed “Fishbed” by NATO, was introduced in the 1950s and became one of the most mass-produced jet fighters in history.
Role: It served as a supersonic interceptor and fighter aircraft.
Variants: The MiG-21 had numerous variants tailored for different roles and environments, including air superiority, ground attack, reconnaissance, and training.
if we are considering current use, The Lockheed Martin F-16 Fighting Falcon holds the title of one of the most widely used fighter aircraft in the U.S. military. It is employed by the U.S. Air Force, Air National Guard, and numerous foreign allies. The F-16 has been in service since the late 1970s and has seen action in various conflicts worldwide. Its versatility, performance, and relatively low operating costs have contributed to its widespread adoption and continued service across the globe.