Disc Priest >> Monk > Paladin > Druid > Holy Priest > Shaman
After Patch:
Disc Priest > Druid > Monk >> Holy Priest > Paladin > Shaman
Not 100% sure about where to put Holy Priests because why the hell would you use one when you can have a Disc Priest? Even when raiding 10man with 2 Heal Priests both should stay Disc. But i think its what i said +-1 Position.
-Disc Priests are #1 HPS on most fights while doing nearly all of the healing with Absorbs and by Dealing DMG... its just ridiculous. They also have very potent Healing/Raid CDs. Patch wont change much. Having a Disc Priest also makes a lot of Enragetimers a lot easier.
-Druids will be great after Patch and the perfect addition to a Disc Priest. While the Priest pushes his HPS through absorbs the Druid is just doing raw healing. After the Patch they also can dish out DPS.
-Monks are the perfect group-healer especially in 10man because they don't need their targets to stand together. Patch wont change much, they are still awesome but druids are a little bit better most likely.
-Paladins are the perfect Allroundhealer atm... after Patch they will still be, but all the nerfs could lead to them being useless if you don't need his support.
-Shamans are the worst healer in 10man period. Even after massive buffs they cannot compete with other healers because their mechanics are very 10man-unfriendly because several people have to stand together and thats rarely the case. Of course there are 1-3 fights every content where Shamans are good (for example Megaera or Ra-den) but even then they get outhealed by monks and priests