By electric, I am assuming that you mean a heat pump. It is really going to come down to how you use the heater. Someone else's conditions and requirements could be completely different than your own so going by someone else could be a mistake. Here are some pros/cons:
Run Cost: A HP can be more efficient than a NG heater so if your gas prices in $/therm are more than about 5x electrical prices in $/kwh, you are better off with a HP.
On Demand Heating: NG heaters come in larger BTU sizes so will heat faster than a HP.
Outdoor Temperatures: A NG heater can be used year around, a HP has limitations.
What good is clear water if the water temperature is to cold to enjoy it? We've answered some questions and provided simple tips to understand pool heaters.
www.troublefreepool.com