I don't know all the scientific stuff, but I think I'd like to at least have maple trees (for wood, syrup, shade), peanuts (peanut butter, peanuts just for snacking, peanut oil), an apple tree, cotton for making clothes, and peas. Nothing like fresh peas from the garden......
When I was in Hawaii I went to a demonstration on the uses of coconut trees, the native giving the talk said that all he needed to survive was coconut trees. The leaves can be used for building shelters and for making rope, the trunk can be hollowed out and used as a boat, and the nuts provide both food and water.
I think you have to have some kind of tree. I couldn't imagine no trees. So, to add to your question....if you were going to select only one tree, which would it be?
Some possibilities with some extra benefits beyond shade, windbreak, wood for construction, cooking and heat, etc.:
Sugar Maple - syrup
Nut trees - pecans, etc
Fruit trees - apples, oranges, pears, etc
It would be extremely hard for me to choose just one......man, this is a good question.