Paladins will remain the most CC'able healer, and unless I am missing something obvious(?). They will be even more CC'able with blessing(hand) of sacrafice being nerfed.
Shamans will be switching roles with them, however, spending the most time out in the open casting. But, as things stand now, grounding and tremor totems will pretty much overcome mosts buffs paladins get relative to shamans by a pretty large margin, at least versus CC heavy teams.
Predicting the following, but will have to see how it ends up in game:
Best healers while being focused:
Priest > Druid > Paladin > Shaman
Best while left alone to cast:
Shaman > Paladin > Druid > Priest
Best while being actively CC'ed:
Druid > Shaman > Priest > Paladin
Mana conservation:
Paladin > Druid > Shaman > Priest
Offensive ability while healing spec:
Priest> Shaman > Druid > Paladin
Just my opinions by what things look like on paper
