Maximizing Voltage with wind power
A wind turbine is not like a constant voltage source, the more current you draw from it the slower it turns. Eventually if you draw too much current, the blades will stall. The question is not how much voltage will it produce, depending on the motor, it may produce the same voltage. The question is, which turbine will produce the most power. For this you have to measure both voltage and current.

$$Power = Voltage*Current$$

The load will make the difference, and the power is dependent on how much torque the blades generate. If your doing an experiment, put a loading resistor on the generator, then put it on the other one. Measure the voltage and the current.