I'd have to disagree but it's probably just because i'm such a fan of this series, i honestly can't think of an arc i didn't enjoy so far (except for the kami-sama-sensei chapters)
I actually thought one of them would be in Kusunoki seeing as her particular ghost seemed benevolent and she's been prominently featured in 2 arcs. The fact that it takes time for the godesses to restore memories puts her back in play.
Ayumi is certainly an healthy possibility as well but i wouldn't count out some of the others just yet, also her newfound crush on Keima would be all more endearing to me if it came without the actual memories.