I don't know wether this is an opinion question or not but I would say Spanish. Of course, it depends on where you live, but Spanish is spoken way more over the world than German. It is in South America, Europe, and even where I live in Miami. If you live somewhere where German is spoken more than learning German would be better. I personally am learning Spanish right now and it is not that hard and a lot of words are the same in Spanish as they are in English.
Im not sure there is such a thing . Doing for others makes us happy so when we do it we are making our self's happy so it is kind of selfish but selfish in a good way.
