The USMC's "B" has incredibly short legs. The USAF's "A" has underperformed in almost every category (even though it is the only version of the 3 that is remotely on schedule). The NAVY's "C" has had constant development problems.
There are serious concerns with the F-35, primarily in range and weight. The A and the C each have issues, the B is really in trouble, IMO. Do we really need STOL? Have the Marines ever used that capability from a remote strip? The B can't vertically takeoff, too heavy. It can only vertically land, and that's on a very well prepared surface. Forget highway strip, it will melt the asphalt. The B also can't land vertically with munitions that it returns with, again too heavy...really? Its so heavy, because if its required STOL gear that it has no range. We can save billions on that project alone.