Actually, a tool that compares texts from different sources on the same topic and ranks them on different criteria could be interesting, i.e. assertion, logical

Actually, a tool that compares texts from different sources on the same topic and ranks them on different criteria could be interesting, i.e. assertion, logical fallacy, emotive language, inclusion/exclusion of key details; very off the top of my head. Additionally - over time you could build up a nice corpus for one source versus another source. I guess you do see studies examining bias every now and then, but the whole thing could be automated and ongoing.