Far too many to mention, but some artists/bands consistently had great B sides, all of which lend themselves to home-made compilations/playlists. Two in particular for me are:
1. Depeche Mode. For me, all 3 of the "Speak and Spell" B sides should have been on the album instead of perhaps Boys Say Go, Nodisco, and What's Your Name. Then there are Flexible, Work Hard, Now This is Fun, and In Your Memory which are all great songs (as indeed are Dangerous, Happiest Girl, Sea of Sin etc from later in their career). However their instrumentals are the pick: Stjarna, Memphisto, Sibeling, The Great Outdoors!, Oberkorn (It's a Small Town) as mentioned already, Agent Orange etc.
2. Morrissey. From Disappointed to I'd Love To to Jack the Ripper to a whole album's worth of great B sides from the "You Are The Quarry" singles.