Aerofoil Section

I think it's dangerous to talk about a best airfoil section without knowing all the parameters involved. You may know that in engineering, nothing is the absolute best... things are always more suitable to something.

By experience, I've seen fans with really complex blades with large dimensions, and some small ones that work fine with more simple profile. THey always use assymetric profiles with chord and angle of attack changing from root to tip (tip always have less angle of attack and less chord, due to higher speed). Take a look at a NACA database at the web for assymetric airfoils that match the characteristics of your application.

This is not too much, but I hope it helps a little.

Such is the reason for "proprietary data" that companies, which have invested heavily in development, guard well. To answer your question may be considered industrial espionage.

Next best thing is to do what seems to be the trend in engineering development for the past 30 years -- buy the best in commerce and copy it.

Please refer ESDU Charts.