In this post tag (keyword) archive you’ll find my posts about my all-time favorite ambient albums. My personal definition of “ambient” is probably quite a bit narrower than that of others. I like to keep the genre definition limited to the mostly beatless stuff. If it has beats, I rather call it chill-out, or just electronica. Others also include (partially, older) sibling genres such as spacerock, new age, krautrock, shoegaze and such in the definition. Boundaries are hard to draw here, but again, if it used to be new age “back then” then it may as well be left to remain new age today. :-)
Calling it “best of” is rather subjective of course – everyone’s taste is different. I’m also fairly certain that many ambient lovers already know these albums anyway, but if there’s one of the other gem among them that you didn’t know, then this compilation has serverd its purpose!