Meg Bowles - her 2011 release, A Quiet Light, is one of the best fusions of space and ambient in years. To release something this excellent after a more than 10 year absence is, IMO, unprecedented.
Richard Bone - I don't think he has ever gotten the level of recognition he deserves. He has had some "average works" but a lot of his stuff is superb and he is a VERSATILE artist.
Michael Allison/Darshan Ambient - If you look at his body of work, whether it be his pastoral ambient CDs like Providence, The Zen Master's Diary, or Autumn Light, or his more recent rhythmic stuff, you can't help but be VERY impressed.
Basically EVERYTHING released on APK's label. Yeah, that covers a lot of ground, but talk about maintaining CONSISTENT quality - sheesh! He's deservedly lauded here at Hypnos but APK (whether what he records himself under various pseudonyms or the other artists he chooses to release) is amazing...also his cover art is frequently beautiful and evocative.
Ben Swire - He's not the most prolific artist but both his Foundry EP, Equilibrium, and his 2010 recording, From Here to There, on Preservation are as good as glitchy yet melodic ambient gets, IMO.
Marconi Union - I haven't heard everything by this enigmatic duo, but Distance and A Lost Connection are moody, urban soundscapes suitable for late night neon-infused cruising by car.
Tristan Feldbauer (and others depending on the album) - I may be the only big fan this guy has but I cannot get enough of his blend of chill/ambient/retro-EM music. His best album, the enigmatically titled Recordings, is one of my all-time favorites. Like Swire's work, it's PERFECT for late night drives down city streets.