Go ahead and have people base it off their opinions of how much they like it, but I actually have information.
The lighthouse boosts your fishing and chances of getting a better fish.
The windmill boosts bug catching and getting better bugs.
Personally, I would keep the lighthouse, because if you chop down all or about 90% of your trees except for your coconut trees, in the summer you'll get all the rare bugs on your trees and you can make up to 100k a run.