the goal is not to talk about who is the "best" healer.
but, what type of healing style is most complex (not in that way, "that type of healing is easy") but in the sort of way like, "can you cast one spell of healing over and over? that isn't complex. if you have to use many type of healing abilities normally often when you heal because the healing is built around it that way like you benefit from it, that is complex.
Healing Touch
Heals a friendly target for <> to <>.
Lifebloom
Heals the target for <> over 7 sec. When Lifebloom completes its duration or is dispelled, the target instantly heals themself for <> and the Druid regains half the cost of the spell. This effect can stuck up to 3 times on the same target.
Nourish
Heals a friendly target for <> to <>. Heals for an additional 20% if you have Rejuvenation, Regrwoth, Lifebloom, or Wild Growth effect active on the target.
Rejuvenation
Heals the target for <> over 15 sec.
Regrowth
Heals a friendly target for <> to <> and another <> over 21 sec.
Wild Growth
6 sec cooldown
Heals up to 5 friendly party or raid members within 15 yards of the target for <> over 7 sec. The amount healed is applied quickly at first, and slows down as the Wild Growth reaches its full duration.
and
Tranquility
10 min cooldown
Heals all nearby group members for <> every 2 seconds for 8 sec. Druid must channel to maintain the spell.
Just like to mention this one also -Rebirth-, even tho it's no healing ability it is sure useful if the tank dies. You kinda get a second chance there.
Rebirth
Returns the spirit to the body, restoring a dead target to life with <> health and <> mana. (With Glyph they can come back with 100% life.)
Now comparing it with the Priest healing abilities...
Circle of Healing (Requires 40 points in Holy Talents)
6 sec cooldown
Heals up to 5 friendly party or raid members within 15 yards of the target for <> to <>.
Divine Hymn
10 min cooldown
You recite a Holy hymn, summoning the power of the Divine to assist you in your time of need. Heals 3 nearby lowest health friendly party or raid targets for <> to <> every 2 sec for 8 sec, and increases healing done to them by 10% for 8 sec. Maximum of 12 heals. The Priest must channel to maintain the spell.
Holy Nova
Causes an explosion of holy light around the caster, causing <> to <> Holy damage to all enemy targets within 10 yards and healing all party members within 10 yards for <> to <>. These effects cause no threat.
Renew
Heals the target for <> over 15 sec.
Prayer of Healing
A powerful prayer heals the friendly target's party members within 30 yards for <> to <>.
Flash Heal
Heals a friendly target for <> to <>.
Greater Heal
A slow casting spell that heals a single target for <> to <>.
Prayer of Mending
10 sec cooldown
Places a spell on the target that heals them for <> the next time they take damage. When the heal occurs, Prayer of Mending jumps to a raid member within 20 yards. Jumps up to 5 times and lasts 30 sec after each jump. This spell can only be placed on one target at a time.
Penance (Requires 50 points in Discipline Talents)
10 sec cooldown
Launches a volley of holy light at the target, causing <> Holy damage to an enemy, or <> to <> healing to an ally instantly and every 1 sec for 2 sec.
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So what would be your conclussion of which class between Priest and Druid has the most complex healing?