What entity type should I choose for a comment type? When I add a comment type (for example, Blog comments), I can select an entity type as target for the comment.
What should I choose and why?
Is it Custom block or Comment? My intuition says to pick Comment, but I don't know on what basis I should decide what to pick.
The other option seems in any case less likely for my case. I just need a global article comment type.
That depends to which entity you want to attach those comments. If the new comment type is for content types (node bundles), select the according type. (I assume it's one of the the last three list entries given in your screenshot.)