Stars of the Lid is the best thing to happen to ambient music since Brian Eno, hands down. This isn't even a discussion. Just sit and absorb this, it's one of the most beautiful albums front to back.
I think Horseback is what REALLY planted the seed for my love of ambient music. It's abrasive and very bleak but with its harrowing traits also comes its emotion that is overwhelmingly powerful.
Taking well Tangerine Dream, this soundtrack was a huge influence for me to purchase my first analog synth. This was my most listened to album 2 years in a row, give it a listen and you'll know why!