As a New England researcher away from home (raised in Massachusetts, but living in Delaware), I find that the New England Historic Genealogical Society gives me the best value. It has extensive records online, has the best publications ever - "New England Ancestors" and the NEHGS "Register" - and other amazing benefits. This will be the first year I actually head to their library during my vacation home.
They charge $75 a year for the membership, and it is truly a great value for a New England researcher who can only do on-site work once or twice a year (and not everyone is as fortunate or able as I am to do that).
SO while I rely heavily on the local FHL and snail mail requests to town clerks (yes, I do it the "old fashioned" way), the majority of my research is done via NEHGS databases.
The Mayflower Society is useful for gathering with like-minded folks at events in your state, and for their publications. The main headquarters sends out the "Mayflower Quarterly" four times a year, and I enjoy the research and information in it. And my local society also sends a newsletter twice a year. I think I pay about $30 a year to belong, but I could be wrong.
The same goes for the Bartlett Society. Surname societies are useful, as they also tend to send out a newsletter a couple of times a year with interesting articles, and any new discoveries.
On-line records and publications tend to be my main reasons for joining different societies. I feel like I am getting "more" if I am getting something tangible in my mailbox. Every new issue of a newsletter or magazine fuels my ambition to keep working!