Well as it's extremely unlikely that Ryanair will base an aircraft in Waterford, I guess you are looking at somewhere that Ryanair have a large base, so it's not impacting a well-performing route. All the better if it's a large base with no route to Cork, so they don't cannibalise an existing route. Porto might fit the crteria. A Polish service may be another option and there's no service to Warsaw from the South