Commenting systems - ease of signup vis-a-vis engagement?

Anybody have an opinion about commenting systems for blogs? I’ve got indecision paralysis with all the options.

I want commenting to be as frictionless as possible. To encourage it.

I’ve used Wordpress(.com) for years for my startup’s and my personal blogs. It’s decent, and I get nice comment discussions. Wordpress doesn’t require an account to comment — just a name and email and the comment is immediately accepted.

I’m thinking about moving to Ghost’s new commenting system requires becoming a member of the blog and signing in by email. Ghost also enables any of the JS-drop-in commenting systems. I’ve been thinking about finding one that allows Google or FB OAuth sign-in to comment.