Cleric for the calling and some combination of classes that involves Sentinel because that is the closest to my idea of a cleric.
The neat thing is, based on what I have read and seen on YOu Tube, you can roll a main, 3 alts and then have all of the callings and potentially all of the classes. THis will make small groups of skilled players very viable for the upper level content without having to be in a guild with 40 wizards, 35 Warrios, etc. I can remember from my EQ days that guilds would try and steal clerics from each other. In the long run, this game looks like it will be much more about the player behind the keyboard than any particular class. But that aside, I always love playing a healer.