On the surface, Germany are the biggest contributors and some EU members get rebates, but taking into account the original idea of a group of trading nations in Europe getting together and thus controlling foreign imports, Germany is the biggest winner.
Their exports are guaranteed within the EU, and their economy is export based..
To keep it simple, for myself, Spain is overrun with German goods. The streets are full of Mercedes, BMWs, VW’s and Audies; indoors there are washing machines, refrigerators, computers, all Made in Germany. Etc, Etc.
Unkindly, I don’t suppose there are many Seats on German streets, or Corbero washing machines or Teka cookers (I’ve just been out to check).