Igneous Flame is good,
Future Sound of London,
Front Line Assembly (Synthetic Forms),
Skinny Puppy (Christianity, Falling, The Centre Bullet, One Day),
Slowdive (Blue Skied & Clear),
Steven Halpern - Crystal Bowl Healing,
Brian Eno - Fractal Zoom,
Snog - Reigning Terror, Supermarket Dream
For me, it's usually artist on certain labels in general, like Touch, Raster-Noton, 12k, etc. Artist: Biosphere, Hildur Guđnadóttir, Jóhann Jóhannsson, Alva Noto, Ryuchi Sakamoto, Scanner, Taylor Deupree or even more mainstream stuff like Carbon Based Lifeforms, Aes Dana, H.U.V.A. Network and old school like Tangerine Dream and some of the krautrock stuff like Popol Vuh (Oddly though, I have never been a Brian Eno fan. Bores me to tears).
Note that my interpretation of what constitutes 'ambient' is pretty broad...
Pretty much the usual suspects - Brian Eno, Steve Reich, Biosphere, some Orb. A lot of the ambient stuff I listen to, tends to be from links on forums or Soundcloud e.g. a guy called Nasoshnik, I've been listening to a lot and another called Pascal Doguet - both well worth checking out.
Everyone should check out a band called Amp. Especially the album "All of Yesterday Tomorrow". Combines many genres like dark wave, ethereal wave, post-rock, space rock, folk, shoegaze, lo-fi and dream pop. Its a compilation but in chronological order in the years they came out so theres 10/10 later on as well.