I'm a member of AOPA UK because I want to support their activities in the UK. Nick Wilcock has been extremely helpful in keeping people up to speed regarding developments regarding the IMC rating, and I was very grateful, so voted with my wallet.
I'm also a member of AOPA US, not because I expect to be flying in the States any time soon, but because the online training courses, videos and AOPA Pilot magazine represent extremely good value for money in terms of what you get.