I'm a member since several years of the USA AOPA organisation and what I receive from them repays my membership several times. I like their training, magazine, laywer support (if you pay a little extra), vref validation of planes and used their escrow service which was cheap, fast and worked without error, just perfect.
I found no reason to join any EU AOPA, I thought about it very good but found none. IMHO it's a waste of money.
I will join the PPLIR organisation though, looks like they are more dedicated to defend the IR private pilots here in Europe.
I'm also a member of ICS, owning a twinkie you just have to. Is their anything for the king air ?