Here's an excerpt from https://www.procon.org/headline.php?headlineID=005330
Pro 1 : The Founding Fathers enshrined the Electoral College in the Constitution b/c they thought it was the best method to choose the president. Using electors instead of the popular vote was intended to safeguard against uninformed/uneducated voters by putting the final decision in the hands of electors most likely to have the info. necessary to make the best decision; to stop states w/ larger pops. from having undue influence; & to compromise between electing the president by popular vote & letting Congress choose. According to Alexander Hamilton, the Electoral College is if "not perfect, it's at least excellent," b/c it ensured "that the office of President will never fall to the lot of any man who isn't in an eminent degree endowed w/ the requisite qualifications." The Founders wanted to balance the will of the ppl against the risk of "tyranny of the majority," in which the voices of the masses can drown out minority interests.
Con 1 : The reasons for which they created the Electoral College are no longer relevant. Modern technology allows voters to get info. to make informed decisions in a way that couldn't have been foreseen by them. Also, while Alexander Hamilton in 1788 saw the electors as being "free from any sinister bias," members of the Electoral College are now selected by the parties & expected to vote along party lines regardless of their own opinions about candidates. Just as several voting laws that limited direct democracy in the Constitution have been modified/discarded thru-out history, so should the Electoral College. As a result of Constitutional amendments, women & former slaves were given the right to vote, & Senators, once appointed by state legislatures, are now elected by popular vote. The vice presidency was once awarded to the runner up in electoral votes, but was changed over time to reflect the reality of elections.
Pro 2 : The Electoral College ensures that all parts of the country are involved in selecting the POTUS. If the election depended solely on the popular vote, then candidates could limit campaigning to heavily-populated areas or specific regions. To win, candidates need electoral votes from multiple regions & therefore they build campaign platforms w/ a national focus, meaning that the winner will actually be serving the needs of the entire country. W/o the electoral college, groups such as IA farmers & OH factory workers would be ignored in favor of pandering to metropolitan areas w/ higher pop. densities, leaving rural areas & small towns marginalized.
Con 2 : The Electoral College gives too much power to "swing states" & lets the presidential election to be decided by a handful of states. The 2 main parties can count on winning the electoral votes in certain states, such as CA for the Dem. Party & IN for the Rep. Party, w/o worrying about the actual popular vote totals. B/c of the Electoral College, presidential candidates only need to look to a limited # of states that can swing 1 way or the other. A Nov. 6, 2016 episode of PBS NewsHour revealed that "Donald Trump & Hillary Clinton have made more than 90% of their campaign stops in just 11 so-called battleground states. Of those visits, nearly 2/3 took place in the 4 battlegrounds w/ the most electoral votes — FL, PA, OH, & NC."
Pro 3 : The Electoral College guarantees certainty to the outcome of the election. If the election were based on popular vote, it would be possible for a candidate to receive the highest # of popular votes w/o actually obtaining a majority. This happened w/ President Nixon in 1968 & President Clinton in 1992, when both men won the most electoral votes while receiving just 43% of the popular vote. The existence of the Electoral College precluded calls for recounts or demands for run-off elections. The electoral process can also create a larger mandate to give the president more credibility; for example, President Obama received 51.3% of the popular vote in 2012 but 61.7% of the electoral votes. In 227 years, the winner of the popular vote has lost the electoral vote only 5 times. This proves the system is working.
Con 3 : The Electoral College ignores the will of the people. There are over 300 million people in the US, but just 538 people decide who'll be president. In 2016, Hillary Clinton won the popular vote by more than 1 million votes, yet still lost the election on electoral votes. Even President Donald Trump, who benefitted from the system, stated after the election that he believes presidents should be chosen by popular vote: "I would rather see it where you went w/ simple votes. You know, you get 100 million votes & somebody else gets 90 million votes & you win." Just as in 2000 when George W. Bush received fewer nationwide popular votes than Al Gore, Donald Trump will serve as the POTUS despite being supported by fewer Americans than his opponent.