Haken - Aquarius
It's still a favourite of mine in their catalogue. Perhaps even #2 after The Mountain.
I think out of their six albums, this one ranks at #4 for me. That said, however, Haken is so consistent in how good their music is that I could easily rank it higher. The Mountain will always be my #1, though (unless a future Haken album is better, which I could see happening). Now that I'm thinking about this, I want to listen to Aquarius again today...