Hey camikazi ! How are you looking to use the heater ? Each of the 2 styles has a really good and a really bad.
Gas heaters extend the swim season both early and late. You wont care if its a bit pricey and you can have a swimming birthday party on Oct 25th. The whole regular season you will care that it costs just as much to run if you use it to make the pool very warm instead of just warm in July.
The electric heat pumps cost less energy wise to use them during the regular season to make the warm pool even warmer. Some people like 90+ degree pools. In season, this is the heat pumps specialty. It will extend the regular season some, but it needs to run 24/7 to do so, it costs much more at that time, and at some point it quits when the gas heater is still working fine.
Raypack heaters come highly recommeded here. Btus make the heat and speed of heating, you'll want the most you can afford for either model with your gallons in CT