Take the A380. On a flight that length it is far more comfortable. On arrival at Narita, it is very possible to clear immigration, collect baggage and pass through customs in less than 20 minutes, and the train station is underground at the airport.
You don't need to worry about convenience with regard to getting into the city; as mentioned by a previous poster, the N'EX is very easy to use and will have you in the centre of Tokyo in less than one hour, which is quite possibly faster than the time it would take to be driven. It's usually a very pleasant train journey - very quiet and not at all crowded, and there is a snack cart that passes through the carriages in case you need something to tide you over.