As many others have said, PROS can be used to program V5, and you have the option of PROS C and PROS C++. As far as my knowledge goes, they are phasing out RobotC along with the cortex, and this talk about RobotC++ and whatnot is actually all just the same thing. I believe that RobotC++ and the VCS version of C++ are the same thing (it wouldn't make much sense to have two different versions based on the same language).
Regardless, if I were you, I would definitely attempt to learn as many of these as possible. The great thing about being given so many language options at this level is an amazing opportunity because you don't get the chance to experiment as much in the work force. I highly recommend trying out as many of these new languages as you can and getting as much experience as possible. The great thing about programming languages is the more you know, the easier it gets to pick up a new one. For most people, once they understand one, learning more and more only gets easier from there.