What are you looking for?
Big, small, lawn art, 10W, 10KW...
I'm going out on the limb this time and say "No Rule of Thumb" for the power it will make, based only on the power it uses, and wind power.
The larger the watts, the better the chances it will do OK.
The cheaper the motors construction, the worse the chances are it will do OK.
The lower the rated RPM/volt, the better it will be. Do not use that for geared motors.
Above 1/4 HP is better. Below 300W is not so great. Yea, I don't know either.
The resistance, RPM/volt, amps/volt, inductance (never listed), etc, is all a consideration.
The larger the windmill, the easier it is to figure a motor.
The smaller a windmill, the harder it is to even guess, because the available numbers don't make sense.
Sometimes rated amps, times are used to gauge the max output before the motor dies.
IIRC, up to 3X the rated amps is possible for before stuff melts.
G-