I like the organization of 123. I makes it very easy to track registrations, payments etc.and I like that it sends automated emails to members when they make a payment within the system or are enrolled.

123Signup is one of the few membership and event management software tools that will work, without customization, for an organization of our size. There are not a lot of options when you need to have member/non-member access for event registration, multiple membership levels, and a parent/child membership structure.