The answer to that question will have several answers depending on what you want?
Is it for hobby or commercial use?
Do you want liability only or Aircraft cover only or both?
What limits of cover do you want?
Do you require European cover outside of your home country?
If you are a certified commercial operator you will undoubtedly need to acquire insurance from a domestic carrier within your own country and provide proof to your countries aviation authority.
If your are a hobby flyer you would still need to carry valid insurance for the country you will be predominantly flying in.