You are much better off using NJ Transit. They have two different lines that stop at the airport station (Northeast Corridor and North Jersey Coast Line) so there are a lot of trains to chose from. Amtrak also stops there but is more expensive and runs on the same track. Both bo from the airport right to Penn Station in Midtown. PATH would mean a bunch of train changes and wasted time. As risenmyth said, 20-25 minutes from the airport station to Penn Station NY and add about 10 minutes to go from Terminal C to the airport rail station.