It's actually pretty strange that the whole cleric series as a whole is more offensive than support, it feels-- but after going Priest there really are no classes after it that can support it very well:
Pardoner has very little to offer that isn't money-oriented, which would be fine for a dedicated build specifically for that, but without knowing what spells would be best to craft and sell, it doesn't seem worth it, especially not on a beta.
Krivis would be an okay match with Priest as it has a couple of nice buffs and a buff extender ability, but it feels weird just running two Rank 2 classes and that's it.
Bokors are completely broken and in a bad way, I have heard. People are saying the summon AI is dumb as shit.
Dievdirby might be okay, but they seem pretty meh overall?
Sadhu is a potential option, but I'm not entirely sure how they work.
Paladin is also a potential option, but it doesn't go with Priest very well, it seems-- unless I lean toward magic use?
Monks seem fantastic, but I'd have to ditch my INT for STR, which doesn't do my Priest spells any favors.
Oracle and Druid both seem like fine final classes, but I have no idea what to put in between-- but Oracle would probably be my choice between the two due to farming funtimes.
Cleric may be okay to go back to, potentially, because Divine Might seems like an excellent skill, though.
Considering:
C-Pri-Pri-Pri-Pal-Or
C-Pri-Pri-Pri-Kri-Or
C-Pri-Pri-Pri-Sad-Or
C-Pri-Pri-Pri-C-Or