naturally u will cap ur Kamihime levels while still needing everything else from eidolon XP, to weapon XP, to weapon skill fodder, to rank points, etc. so u will end up levelling all the Kamihime u have anyway.
but for breaking limit, it definitely best to focus on most useful first. in short term, probably all the SR you have to first uncap so u get their 3rd ability.
by the time u want to decide whether 1 element or equal progression or whatever, most likely many of ur kamihime will already be 3 star uncap and waiting for event for final uncap material.