Which one is more cost effective run 110 volts or 220 volts swimming pool pump?

Whenever you have the electric available to do so, always choose the higher voltage. Reason being if you look at the spec plate on the motor you will see that the amp draw is significantly less when wired for 220.

In some cases depending on the horsepower and the brand the difference can be as much as half. Lower amp draw equates to a cheaper operating cost.