The answer to that depends to a large extent on your location. My suggestion would be to look for trees that are – as far as possible – local to the area. Exotic species (which have been imported from other places) may seem to fit the bill, but they usually don’t integrate with the local ecosystems. For example, a lot of people plant exotics like the so-called “Australian Teak” [Acacia mangium] or Gulmohur [Delonix regia] because they grow quickly. However, there is a large question mark over long-term effects on the soil fertility. I think it’s better to have a slow-growing native tree that doesn’t have negative side-effects.