Originally Posted by
Xentropy
Via SimulationCraft data, mostly T9 gear but T10 mechanics.
Spec|Crit Scaling|DPS-neutral Scaling
Frostfire|1.8613|26.585
Fire|1.6858|22.873
Shadow|1.5419|21.995
Elemental|1.3957|19.033
Balance|1.2512|17.273
Affliction|1.2487|15.851
Arcane|1.1548|14.899
Demon|1.1272|14.856
Destro|1.0391|13.519
Frost|0.7932|12.113
Most of the bulk of the center of the list are pretty close together in value, so ignoring specs you basically never see, a good rule of thumb is fire mages first, then shadow priests, then elemental shamans, then balance druids or affliction locks, then anyone else. The typical arcane circle-jerk philosophy is very much suboptimal. These scaling factors already take into account normal well-geared dps per spec (balance druids should get about the same dps per crit% as affliction locks even though their base dps is much lower), but if your particular potential target does significantly lower dps than even the theoretical average due to lack of gear or skill, that'd need to be factored in to your situation as well.
(Ninja'd, but since I sorted the data from the same source by value I'll leave it here for convenience.)
(Edit2: I added DPS-neutral Scaling to the chart. This is the DPS a player should gain by receiving your Focus Magic per 1k of their base dps. Basically, multiply the DPS-neutral Scaling value of the appropriate spec by the DPS (in thousands) that player typically outputs in your raid for each respective potential target and the result should be how much their dps increases due to your FM. e.g. You have a boomkin and an affliction lock both doing 9k on Festergut. Multiplying their DPS-neutral Scaling by 9, the boomkin can expect to gain 155.457 dps while the affliction lock would receive 142.659 dps from the buff. While the base scaling values of boomkins and affliction locks are similar, if you have a boomkin outputing the same dps as your affliction lock, the boomkin should definitely get the FM before the afflic, since the afflic *should* be doing more than that, or the balance druid less.)