Ben,
Spot on comments about giving the customer what he wants!
More generally,
While I am less convinced about the efficiency of semi-trailing arms and even less about live axles (actually I call them dead axles, I always have been convinced that you can make a good car with a McPherson.... but if you if you miss the window of good mix between of tire exploitation and kinematics design it will be more difficult to make a change. Providing some suspension pick up points adjustability, with a 5 links or a double wishbone you can get and/or adapt the heave and roll camber variations, roll centers, pitch centers position and movement to what the tires (and good drivers) "need" much better than with a McPherson. And if for whatever reason you are forced to switch to another brand of tire, your design could not be adaptable...
As a student I will most probably go for a double wishbone or a 5 links. As a design judge I regret there is a lot of monkey see monkey do and often students cannot explain WHY they choose the suspension type they use.