>>1172586From Stanstead? Based on this Ryanair destinations map?
Probably Belfast International. I mean, "Westeros International". No customs or anything since domestic flight, but public transport is in the form of the Bus 300 from Belfast International to Belfast Great Victoria Street/Europa Buscentre. Bus fare is pretty cheap though, and you're on the new bus to Belfast.
Next one (from that map) is Berlin Schönefeld Airport. The train station is about 500 metres away from the terminal building, and you can use the RegionalBahn, RegionalExpress and the S-Bahn from the station to the city centre, including Berlin Hauptbahnhof.
Generally speaking, there's not a lot of shitty airports other than Hahn, Girona and probably one or two others.