MoP Priest PvP - Cascade or Halo?

[Owltoid]

Assume you have four going off at once in PvP. Which talent do you choose?

http://mop.wowhead.com/mists-of-pandaria-talent-calculator#p

Cascade can be cast more often, costs less mana, and basically acts like a massive chain lightning.
Halo is basically a super holy nova.

[Ualaa]

Looks like Halo will both heal allies and hurt enemies, while Cascade can either heal or harm but not both at once.
What will your team be lacking the most, big offense or defense cooldowns?



Nothing says you cannot mix and match.
At some tiers, my Druids plan on going 1x 3x 1x... or 1x 0x 4x, etc...