FX.3A Sea Harrier
The Harrier was intended to be replaced by the newer F-35, however with endless delays, budgets overruns and 10 new problems for every solved one, the UK decided to abandon the program, and instead refit the existing Sea Harriers to the FX.3A version each at the fraction of the cost of a Lightning II.
The FX.3A variant features of a cyclotron plasma beam cannon, omnidirectional LIDAR sensors and a CAPTOR-X AESA radar. It's powered by a Rolls-Royce Pegasus II engine, which is essentially a Pegasus engine rebuilt with the latest materials. Additionally, the hull has a radar signature reducing shape.
The result is one of the most advanced strike fighter in the world.