Is the BBM manifold the better one to use or am i better off making a sheet metal intake with tuned runners

I'd say stick with the BBM. Ford have retained it after the EF in the EL, AU, BA, BF. It certainly gave my XH a good torque improvement in the 50 - 70 kmh speed range over the log manifold.
I think redesigning something that has been a proven performer might be a sideways step.