I gotta throw in my two cents…
I honestly do not believe that it matters… Any more. In the past this was must probably true. But, electronics and electrical quality have definitely improved over time.
Also, there is a vast majority of new model (last few years) that actually have dc motors instead of ac motors.
They are more efficient, less noisy, and last longer. They after powered by the dc rectifier and it really doesn’t care of the a.c. Is 90v or 120v. As long as the incoming a.c. is within the upper and lower limits of the rectifier it will produce the exact same voltage every time.
Also, if your ceiling fan is ten years or older, you would be best to replace it. The annual savings is rather dramatic.
Most ceiling fans run 24/7.
An older fan on high easily draws 60w. This at 12.5 cents per kwh = approx $66.00 per year
A new fan on high draws about 22w. This at 12.5 cents per kwh = approx $24.00 per year
Now, count the number of fans in your house.
If you have 5 fans running 24/7 that is a lot of money.
Buying a new ceiling fan can pay for itself in monthly savings in one to two years, depending on variables.