Your weights on a one-minute single-boss fight: 14.3 Healing power for each 1 % of spell crit and 36.4 for each 1 % of casting speed. A point of MP5 weighs 0.05, a point of Intellect 0.35 and a point of Spirit 0.29. They come from the benchmark set itself: each is what one more unit of the stat adds to that exact gear, counted in Healing power.

Mana stats

Intellect is 15 mana a point, and 59.5 of it is 1 % spell crit. Mental Strength adds 15 % to all of it. Spirit regenerates 12.5 mana plus a quarter of your Spirit every two seconds, and you keep half of that while casting through Meditation. Spiritual Guidance also turns a quarter of your Spirit into healing power. MP5 keeps flowing in full while you cast, which is why a point of it outweighs a point of Spirit on long fights.

These three only count once the fight outlasts your mana.

On a one-minute single-boss fight the single-target build never runs short, so Intellect falls to 0.35 and MP5 to 0.05.

Crit

A critical heal lands for 150 %, and Holy Specialization gives your heals 5 % more crit chance.

A three-minute fight values 1 % crit at 7.66 Healing power. A one-minute fight values it at 14.3, because every crit there is a bigger Greater Heal you have the mana to cast.

Casting speed

Casting speed shortens Greater Heal, Heal and Prayer of Healing. On one minute, where you cast your biggest heal all fight, 1 % of it is worth 36.4 Healing power. On longer fights it mostly empties your bar sooner. Your sources are Troll Berserking and the Minor Haste glove enchant.

On every fight

Gear for the length you raid: the longer the fight, the more Intellect, MP5 and Spirit count beside healing power.