Electric of conventional engine fans

Just wondering whats out there, which is the more desirable choice in cooling? Electric? or convention flex/clutch fans? Does any one know which is the more horspower hungry of the three? I am thinking of going back to an engine fan (flex fan) instead of electric. They say you get better cooling with the conventional fans but at the price of horsepower. I'd like to get some opinions.
Regards
Billy D...