Cheapest easy train option is Yamanote line to Keisei Nippori and take the Limited Express. Connecting at Nippori is much easier, inside the same building with escalators, rather than going across the street at Ueno.

Keisei Limited Express 1030yen . It is commuter train but lots of empty seats and room for luggage, leaving Nippori, as long as it's not early morning rush hour.