Originally Posted by
goldelite8
Do not buy a ticket on Amtrak. You will not get to NYC any quicker than if you were on a NJ Transit train. If you're not traveling during rush hour, I recommend the bus (Newark Airport Express). It's a few dollars more, but more frequent and also quicker than the AirTrain connecting to the train.
I agree about the bus, but OP said he'd be arriving on a weekday morning -- traffic could be pretty miserable depending on what time he means.