I think Robot hit it pretty much on the head, a lot of it depends on the build, location and type of driving.

My own experience is nothing moves more air than an OE 7 blade fixed fan with the most pitch you can find, HD fan clutch and shroud. The down side is they they take a fair amount of room due in part to the thickness of the clutch, require a lot of belt wrap or 2 belts and make a fair amount of noise due to the amount of air they move. They also take the most HP to turn when the clutch locks up.....but if the engine starts to heat up do you really care?