My favorite was Opera Sauvage. It had a flow and consistency that was, for me, unique in his works.
He will be missed.
Yes what remarkable, 'organic' sound. Also 'l'apocalypse des animaux' and his other early albums really. Despite being old synths, they still sound classic
Also, if you don't know about it yet, check out his collaborations with Jon Anderson, as Jon & Vangelis, two awesome musicians at their peak.
What a pity...