Hyperion has the best UI and decently tagged music (Score 1)

http://hyperion-records.co.uk/ http://www.theclassicalshop.net/ http://linnrecords.com/ http://www.dacapo-records.dk/ and http://www.analekta.com/ http://www.classicsonline.com/ absolutely deserves mention, but has little on flac http://www.passionato.com/ and http://www.deutschegrammophon.com/ are good, but don't provide booklets