The Electronic Panorama series are pretty good (although if you want them on vinyl you will have to spend a bit of money, I have and I think they are well worth it). Ivo Malec, Bernard Parmegiani, Pierre Schaeffer, Pierre Henry, Francois Bayle, Alireza Maschayeki, Jacob Cats, Maki Ishii, Krzysztof Penderecki, Andrzej Dobrowolski, feature on the compilations to name a few.
Toshiro Mayuzumi.
Helena Gough is one of my recent personal favourites.
Morton Subotnick.
The "OHM - The Early Gurus Of Electronic Music 1948 - 1980" compilation is really worth getting too.
Todd Dockstader.
Bo Anders Persson.
Curtis Roads can be quite interesting.
David Tudor, most notably the Neural Synthesis recordings.
Ragnar Grippe early stuff, and Åke Hodell.
Janek Schaefer.
Quite a few great releases-artists have been mentioned already.