That's what I like about this place --- simple questions sometimes stir up valued answers.

Considering most vehicles are traveling and the air is passing toward the motor, I feel enhancing this air volume/flow is most efficient with the puller - no fan assembly at front to block air flow.

On the other hand, a stationary scenario might lead one to conclude the pusher will do fine, though... it may be drawing engine compartment temps higher than exterior ambient levels through the radiator slowing the cooling process.

Each location choice, is influenced by the static ambient temperture at the radiator front fins. Comparitve results may not prove to be that significant so .............

Where the hecks that cooool red-haired chick from Myth Busters when you need her?