In PVP Templar can probably do the best burst healing, but as an alternative there are warden healers that have access to some different important debuffs (specifically major defile) that make it an interesting alternative. They rely more on healing over time versus the big burst healing. Both have their place in a pvp raid group though. Nightblade dd that also provide passive healing from doing damage are also very helpful to a solid group dynamic. Funnel health, refreshing path, and sap essence all combine into relatively decent group healing when diving into larger groups.

As far as PVE goes I think templars are still the kings. Wardens can generally get a role as off tank but haven't been as accepted there as healers. NBs and Sorcs do well enough in dungeons but you wouldn't see them healing in a trial.

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As another alternative DK's can provide ample healing as well. They seem to be more of a shield, then heal the difference along w/whatever the resto staff brings.