My opinion, and I must emphasise that it is only an opinion, is that A-levels are really just ways to demonstrate to Universities how well you can absorb and retain information.
If I were in your position I'd be thinking about which course I was most likely to obtain the best grade in as Universities are interested in your accumulated grades at A level much more than the subject they were acheived in.
Perhaps it would be beneficial to consider which University courses interest you the most and then decide on your A-level based on the criteria for admission onto that particular course.
If you feel you are more likely to gain an A or B at A level in Media Studies than Film Studies then I'd be inclined to plump for that option. After all, if you get 3 or 4 As at A level then the University doors swing open much wider than if you're appying with Cs and Ds.