Thermo fan blade design - which is best; straight or curved blade?

[4x4coaster]

Hi all,
I've been trying to determine which is the most efficient electric fan blade design for thermo fans; there are basically straight blades or the swept curved blades.
I have found sellers who both claim their shape is more efficient than the other. Most agree that the swept blades are quieter, I just want the one that moves the most air.

Lets hear it from someone with an engineering background who can give the unbiased facts instead of just marketing hype,
thanks in advance!

 

[pugslyyy]

The molded blades have the ability to be better. Since the outer edge of the blade is turning faster than the part closest the hub you can optimize the design for the differences in speed along the radius.

 

[155mm]

The curved ones are more efficient. Take a look at the fans on computer graphics cards. Those things put out crazy amounts of heat, which is why most of them have 2 or 3 fans built right on top of them.

 

[jomobco]

I believe the curved blades give you a greater surface area.