Exactly what it says on the tin. I think Air and Summer are tied for first, (Which I think speaks for themselves) but out of Dream, I think my favorite is Minagi's. I think my favorite part of the arc is that it wasn't a curse from long ago, like Air and Kano's Dream was, but the fact it was all immediate.
Also:
Spoiler: Highlight to view
Minagi's mom isn't the only one forgetting Michuru never existed, but Minagi herself.
The drama was a lot more intense in my opinion because of this.
