Personal anatomy has a lot to do with how comfortable a saddle is. Brooks saddles have the advantage of the leather gradually moulding to fit your anatomy while plastic base saddles do not.

Of the plastic base saddles I have used the Fizik Airone that came stock on my Civia Hyland is the most comfortable I have tried. This includes several Rolls I used to use prior to discovering Brooks saddles. I find the Airone comfortable enough so far that I have not felt the need to change it.