> Maybe you'll say that the EU is great for small countries and not so much for larger ones, who are sponsoring the EU's success with their citizens tax money.

It's not that easy. Germany sponsors quite a lot of EU, however due to Germany's economic position the EU enables a lot of business across Europe with low friction. If Germany still had its own currency it would be too expensive for other countries, not to mention customs and common regulation.

For the citizen however it is mostly noticable by foreign workers migrating here, while going to Spain (Mallorca) or Italy for vacation is easy.