unfortuntely there is no right plugin available for free that best support to manage wordpress membership site .
Whils most of the free membership plugins have have various limitations like paymant integration ,SEO promotional lacking other premium plugins like memberwing,wp-member,amember have protected thier plugin with encoding so it you can modifty the code as you want so it will not be felixible sit and manage from your blog
finally i found a premium wordpress membership plugin(aff) comes for 35$ ,threre are lot of other good things but only thing i can specify here is ( the source code is not encoded ) so it can be easily integrated with your blog than other membership plugins
