I guess there are 6 methods to get Tokyo Station from Narita.
2 Trains: JR Narita Express, Keisei Skyliner
3 Buses: Access Narita bus, Airport Limousine bus, Keisei bus
And taxi! Taxi is the most expensive choice, it's about 23000-25000JPY.
The trains and buses are clean and comfortable.
Narita Express is very clean, comfortable and easy to find the way out. Highly recommended method to get to Marunouchi from Narita.