I think everyone is actually missing my point on the F-35.
Kinematically the F-35 is a dog compared to F-22 and it will be so against other 5th generation fighters like J-20(once WS-15 engine is installed if not already), or the others that will come online over the next 10-15 years.
No amount of upgrades will allow the F-35 to super-cruise, dramatically increase it's top speed or supersonic manoeuvrability.
The fundamental argument is why buy F-35 right now when the current 4th generation fighters are good enough and just wait a while longer to buy a true air-dominance fighter?
As an example, the UK has ample technology to develop a real 5th generation fighter and I have no idea why the idiots in charge thought it would be a great idea to put the F-35B on the aircraft carriers. Fine if it only has to fight 4th generation but what if say in 2030, it comes up against an enemy that has 5th generation fighters that are optimised for air-superiority? F-35s would be shot down in droves and the carrier itself may even get sunk as it would have lost it's fighter cover.
It seems that every moron jumped onto the F-35 since the US was manufacturing it and so it must be good! The RAF wanted a squadron(24) of F-22s in the 1990s as they saw the inherent weakness in F-35s air-to-air capability but this was turned down by the Americans. At that time the government in charge should have launched a program in conjunction with other European countries like Netherlands, Norway etc to develop their own 5th generation fighter.
Even a 5th generation fighter that had a relatively lowly R&D budget(take whatever suitable from Eurofighter like avionics, radar and engines) would have been far better than the F-35 but alas there was no true leadership around at the time.
nobody knows what the J-20 is capable of. it is unknown commodity like all Chinese aircraft. exception is the JF-17 which has been shown to dozens of prospective customers.
the f-35 has been evaluated by scores of professional air forces in the west