Most spoken language in Europe: German Language most useful in Europe: English, as German is not much used in other. There are of course regional differences. In Italy, Spain and Portugal English is less spoken, likewise in Eastern European countries English.

In many modern countries, english is taught when kids start with school so in countries like Sweden, Austria, Swiss you can perfectly go along with it. German is valuable in my opinion as well cause it´s the official language of 3 european countries plus a minority language in some of their neighbour countries.