According to the index created by Global Firepower (GFP), the military power of European Union countries in 2018 is:

1. France.
2. United Kingdom (UK).
3. Germany.
4. Italy.
5. Spain.
6. Poland.
7. Greece.
8. Czech Republic.
9. Sweden.
10. Netherlands.
11. Romania.
12. Denmark.
13. Hungary.
14. Finland.
15. Bulgaria.
16. Austria.
17. Slovakia.
18. Portugal.
19. Belgium.
20. Croatia.
21. Slovenia.
22. Lithuania.
23. Latvia.
24. Estonia.
25. Ireland.

Reference

GFP (Global Firepower) (2018) European Union Powers Ranked by Military Strength. Available from World Wide Web: https://www.globalfirepower.com/countries-listing-european-union.asp. [Accessed: 02 May, 2018].