The four strokes aren't any harder to start than a 2 stroke.
We have had 30hp Merc 4 stroke pull start motors at the lodge on Great Bear for quite a few years.
If they are maintained they start first or second pull.
However, having electric start is a huge bonus as you will have a battery and charging system which will mean you have power to run lights, fishfinder, radio etc.
If it were me I would go with the electric start 20hp Merc.