Rayray

Holy

For me:

Int > SP > Spirit> Haste > Crit > Mp5 (my personal opinion for my gear/healing)

As a main spec holy priest I personally am in love with spirit. I've put spirit quite high up on the stats here, though it really does depend on your gear. As I've got quite alot of SP, I go for more spirit for the mp5 aswell.

Now you may have noticed I've put Mp5 last, the reason behind this is mainly down to how I heal and how I time Shadow Fiend/Hymn of Hope/Innervate (<3 kitties)/Pots. Now this doesnt mean to say that you dont need mp5, I've currently got mine at a steady 320 and aslong as I dont go below 300 I should be fine.

My general way of thinking is that if its a long boss fight I want to use my shadow fiend as soon as necessary so that I will be able to use it again during the fight. Doing this method allows me to usually have my shadow fiend for the first phase and the last phase, this is good because in most cases the last phase is the hardest. If I am in need of mana during the middle of the fight I will use Hymn of Hope and/or pot.

If it is a short fight I would save my shadow fiend until the middle of the fight to get the full benefit from it.

Disc

For me:

Int > SP > Crit > Mp5 > Haste

Disc is my dual spec and I havent had as much experience with it as holy. Int is the obvious choice for disc as it provides crit, which is yummy for disc healing as it generates shields/armor. As you'll most probably be healing a tank as disc SP is also a good choice as it boosts your shields absorb amount.

As disc you wont be using Greater Heal, instead you will be using flash heal/penance so while haste does add something, it benefits holy more.