I would prefer to live on the plain.
First I like wide open view.
Second, the plain usually has fertile soil on which I can grow food and feed animals.
Also, if I have a car or some sort of transportation, I can easily go around to explore surrounding area.
Living in the forest is also wonderful.
But I just don't like the moist climate there and mosquitoes.
And desert is definitely a bad place to live, because I may not even have enough water to live.
Looking back at the history of our civilization, many cities and kingdoms were originally found on the plain area.
Therefore, I believe the plain is also the most suitable for us to live among there.