it's a hard call to either listen to a dozen air forces or a forum guy
RAF - F-35 (Joint Strike Fighter)
The JCA will place the RAF at the forefront of fighter technology and will give it a true multi-role air system that will surpass the majority of other weapons systems in production today.
This will give the UK a world-beating land-based and sea-based joint expeditionary air power capability well into the middle of the century. When the JCA enters service, it will be able to conduct deep strike missions, into contemporary Integrated Air Defence Systems, against a myriad of target sets. Moreover, by conducting robust Integrated Air Operations, JSF will support friendly ground forces with close air support, long-range interdiction, anti-surface warfare and tactical reconnaissance.