i'll honestly be shocked if it's not Shiva
and i'll look pretty stupid

but my bets are Shiva > Osiris (really, DMM players are pretty much 100% confirming it..)
also, Thanatos is in need of an awakening now that DMM's Amon Unleashed's debuff is now C frame...
Enma is in need of an awakening, but doubt it for a while as they recently had Acala... and they released [Wind] Enma in DMM.

Marduk, Cu Chulainn, Raiko, Aphrodite and Raphael are all overdue one. Hopefully we can see one of them being awakened after Osiris and Shiva.