I would LOVE a babelfish because I never forget my towel and three pints of beer before hitch hiking sounds like a bad idea, but I think I would like it to be beneficial.
I think we would certainly benefit from a long living species like the Tolkien Elves. They would have a better sense of history and perspective on the world and could, perhaps, help stop our societies from repeating it’s typical pattern of ‘Fast Food’ political and social choices.