Both of these WordPress membership plugins will enable you to protect and sell your content, but each will have their pro’s and con’s when compared.
Wishlist Member has many more integrations, where Restrict Content Pro is focused mostly on WordPress only.
A perfect example is Wishlist will integrate with ThriveCart, 2Checkout, and a list of other SaaS-based cart platform. Same goes for email autoresponder services, Wishlist integrates with many more.
However Restrict Content Pro is much more refined and easier to use. The interface is elegant and well thought out, where the interface and user experience in Wishlist could be improved.
Wishlist has better pricing on their annual license, but Restrict Content Pro has better pricing if you want unlimited websites or you wanted a lifetime license with lifetime support.
For me, I would choose Wishlist over Restrict Content Pro except in the case where I needed to use a hosted shopping cart.