To me, the case for getting rid of the electoral college is so straightforward as to hardly need articulating. Arguments about a straight first-past-the-post popular vote versus some other kinds of systems involving runoffs are things where reasonable people can disagree, but the electoral college is just an absurd anachronism rooted in an 18th century understanding of the nature of the country that hasn't been applicable for a long, long, long time. But if you want a really exhaustive account of the harm done, check out FairVote's report "Presidential Elections Inequality: The Electoral College in the 21st Century".