Clutch Fan!

I feel that clutch fans are the best choice there is as far as cooling fans are concerned.

Flex fans have a couple inherent problems. The first is that they spin proportionally to the engine rpm and have been known to abruptly disintegrate if subjected to high rpms consistently.

The second issue is that flex fans flatten out and stop moving much air at higher rpms. So, if you have a high-load, slow speed situation where the engine is working hard at higher rpms, the fan will not move enough air. That's why you NEVER see trucks and vans with a flex fan. They all have clutch fans, at least after air conditioning became common.

I personally am unconvinced that electric fans are worth the trouble. You have to have a large enough fan(s), all the wiring and a controller, and I don't think it's free horsepower. The alternator has to keep the battery charged, and that takes engine power to do so. The main reason the OEM's used electric fans was space considerations.

The clutch fan loafs along undriven until the temp rises, at which point it engages, and I find that roar comforting, not annoying because I know it's pulling loads of nice cool air through my radiator.

Be aware that there are two variations of fan clutches- thermal and non-thermal. The non-thermal do not respond to temp variations and stay about 80 percent engaged all the time.