Beast Mastery Question. Mastery or Haste? - Builds, Talents and Class Mechanics - Hunter Forums

Lilatha is pretty much correct. Here is something I quoted from Elitist Jerks who are the best number crunchers around.

Relative stat values

Agility
Your best stat, by far, with the possible exception of hit. One agility provides 2 AP and 1/324.85 critical strike percent, before scaling. You get 5% extra from wearing all mail, 5% from raid buffs. The AP is again increased by 25% by Animal Handler, the passive BM benefit, and 10% from raid buffs. Agility is so much better than any secondary stat that some Wrath enchants that are pure agility come out significantly ahead of the 50 and 65 rating points in masterym crit or haste that newer enchants give.
Hit
Gearing for the hit cap is generally a good idea. Ranged attacks have a 8% chance to miss against mobs 3 levels higher than us and each point of hit rating gives us 1/120.109%, so we need 961 hit to reach this, or 841 for draenei. The consensus is that it is better to be slightly over than slightly under the hit cap
Attack Power
Raw attack power is going to be rare, but still exists for some enchants, Pure AP is the slightly better than crit/haste/mastery point for point.

Crit
Almost all abilities crit for 200% damage, or 206% damage with a [Chaotic Shadowspirit Diamond]. Some exceptions include Explosive Trap and Serpent Sting which uses spell crit damage (and crit chance) – 150%, or immolation trap which cannot crit.
Mastery
Mastery affects all damage done by our pet, including Kill Command, and each point of mastery increases pet damage by 1.7%. Mastery beat out haste by a fair margin (3:2) when looking at each stats contribution with the mentioned gear previously, but is now showing up more or less on par with haste.
Haste
Haste affects both the speed of your shots (cobra and auto) and your rate of focus regeneration. You need 128.057 haste rating to get 1% haste. Haste effects generally scale multiplicatively. If you have 32% haste from gear, 3% from Pathing, and Rapid Fire, a base casting time of X would now be X/1.32/1.03/1.4. Procs that increase haste rating will stack additively with your total haste rating value (32% in this example). Focus regeneration appears to be a base of 4 focus per second scaling multiplicatively with haste; i.e. 30% haste would be 4*1.3=5.2 fps. You will likely not see a huge increase in focus regen from upgrading gear.
Mastery or Haste?
The recommendation from this guide currently is to reforge to crit when not present and doing so from the secondary stat with the largest amount of rating. If crit is present with haste or mastery, the current recommendation is to not reforge out of it (except if below hitcap as reforging will outperform gemming for hit)