http://www.theguardian.com/tv-and-radio/tvandradioblog/2010/jan/12/guardian-50-television-dramas?guni=Article:in%20body%20link
Even though its from 2010, this is a very good list IMO.
But to bring up to date, you`d have to add Breaking Bad, The Killing, The Bridge, Borgen plus maybe a few...