First of all EWR is the oldest NY airport, actually it was NY's first airport way before Laguardia or Idlewild/JFK were built. It was also the first airport in the Country (maybe even the world) with a control tower, paved runways and runway lighting.
If your in Times square, LGA is the closest at about 8-9 miles, EWR and JFK are almost the same distance from Times Square at about 15 miles. However if your talking about the West Side, Lower Manhattan, Wall Street, Greenwich Village, Chelsea, Tribeca or the World Trade Center area EWR is the closest. From EWR to the World Trade center is about 8 miles.
Upper East side residents of Manhattan are closer to LGA and JFK, Brooklyn and Queens residents will natuarally prefer LGA and JFK. For Staten Island residents EWR is closer and cheaper to get than JFK or LGA, and alot quicker too. To get to JFK from Staten Island you have to drive the Belt Parkway one of the Citys most congested highways, LGA is worse.
For people who live in the Bronx it's about even between EWR and JFK, to get to EWR from the Bronx you have to cross the George Washington Bridge. To get to JFK from the Bronx you have to cross the Tri-Boro bridge, both are toll roads and both are natorious for traffic.
EWR , because the way the highways are set up draw lots of travelers who live in Eastern Pennsylvania like Bucks County and Southern NY State like Rockland and Orange counties. On anyday walking through EWR's parking lots you will see many Connecticut plates.
Now with EWR's Airtrain, EWR is by far the most conveinant aiport in the region. NJ Transit serves the airport 3-4 times an hour from NY Penn Station, from Manhattan to Terminal C at EWR takes 30 minutes. Amtrak serves the airport every hour from as far North as Boston, as far West as Harrisburg and as far South as Newportnews and Charlotte. Philadelphia is 50 minutes to the airport on Amtrak, 1 hour 20 minutes to Stamford CT, 2 hours 45 minutes to Harrisburg, and 2 and a half hours to DC.
Eastern Air lines flt # 701, EWR-MCO Boeing 757