I was doing a similar research an year ago.
Cheapest EU country just for Profit Taxes is Bulgaria. There you are paying just 10% as taxes. But still the money remain company's money. If you want it clean for you, you need to pay 5%-15% dividend taxes. In Bulogaria you need to pay and monthly ~80 social taxes. It's mandatory.
Another good options are Malta and Croatia. For example in Croatia you could have a company and you are not obligated to pay yourself a salary (taxes respectfully).
when talking about bitcoin profit taxes, which is usually paid by private people, not companies, it might be better to look for a country where there is no tax on bitcoin profits at all.
I heard Denmark has no tax on it and Netherlands only 5%.
But I can not confirm this, only rumors.