I fly all types, but my opinion is:
If it's real little electric is the only way to go.
20 to 60 size either nitro or electric is fine, electrics are winning me over here though.
60 to 120 size nitro wins with me.
120 and up gas is the only way to go.
Down on the tiny side if you don't want to do electrics go diesels they are way cool. I have a .033 that will idle for 15 minutes then go full power without missing a beat, try that with any other ICE, but they do stink.