I looked at a number of the membership management plugins. I wanted to be able to record custom fields in the member record and easily report on the status of the member base. Some member management systems serialize their data which requires more effort when wanting to view or export the member list. WP-Members uses the WordPress user and usermeta tables. You can view and export their contents using the standard user management functions of WordPress. The basic documentation that you get when downloading the free version is good, but the members-only documentation is much better, worth the $47.