As to whether EWR offers easier access to Manhattan than JFK, I for one will take JFK every time. Backups at the Holland and Lincoln tunnels from 6am to 9pm are the norm, and there are unfortunately not any really viable alternate routes for downtown or midtown. JFK, on the other hand, can be accessed from many different roads so when there's a backup or accident on one you can easily divert to another. I myself avoid EWR like the plague! ;-)