Ozone is definitely my favourite Planisphere, and he never really did anything else like it. The airy, echoing FX are very distinctive. A few underrated Planispheres IMO:

Memories of the Light
Legacy of Time
O

'O' in particular is great, an epic 15-minute builder which doesn't kick in until the 10-minute mark. Easily the biggest track length/track title ratio I've come across, too!