Ford spends millions of dollars in research and testing on every vehicle it develops and they do alot of this at their Arizona Proving Grounds to make sure they can keep themselves cool.
If all the components are in good working condition there is nothing else out there that will out perform the stuff it came with. That said you need to do your part on making sure the rad is clean and clear inside AND out, fan shroud is on, clutch is working right,coolant is clean and full, thermostat is working and even making sure the tune up is good and ignition timing is set correctly.
Now thats not saying a electric fan or flex fan wont work. The problems I have seen is electric fan controllers that fail, fans that dont pull enough cfm, motors that burn out from water or dirt getting in them and crappy ways most people mount them that can damage the rad itself. And a flex fan will work but the noise and power robbing make them not a great option. They can rob as much as 30hp and on a motor that barely makes over 100hp thats a huge lose.
Just my $.02