I've had both and given a choice and price being nearly equal I'd go with the electric. Much easier to deploy and retract and you won't bang your head on the support arms. Most folks complain about the electrics because they can't tie them down like to old manual awnings.
However, on the ones I've had, tying them down was not necessary. Even in a good wind the awning folds in half after there's enough wind force to compress the gas spring. Then all the wind dumps out and the awning returns to it deployed position. Does the same thing when water ponds on top.