I love Eventide ambience in general, and I've always liked the Blackhole algorithm.
Not so interested in a Microtune setting for tails that go sharp after a second or so.
But that's just me.
I bet that sounds great! Right now, for those sounds I use either the Silver Lake reverb, the Fractal FM3, or the HX Effects. I think some of those trippy sounds could be done with a multi-effects like the Plethora X5 as well. Combining pitch shifting on reverb tails and echoes requires a purpose-built pedal like the Black Hole, or several resource-hungry effects at once.