My comments relate largely to news media:
(1) Availability, Accessibility - the more accessible, the larger penetration if information.
(2) Credibility (of media). The more credible the source, the more willing the public will be open to the information communicated.
(3) Diversity (of media outlets) - The more diverse the less polarization of public opinion. Diversity interplays with (2) credibility. I am unsure, but diversity may actually be inversely related to influence. The less diversity (for instance, a Communist==dictatorship country with a single media outlet), the stronger the control power (but less credibility at the same time).
In general, it should be desirable to maximize the three factors above for a well informed, civil society. In particular, news media's role should primarily be to inform, and not to influence.
