How should Definitive Cat DPS gear?

As mentioned at the top of this FAQ, the best answer to this question is given by two utilities:
Toskk’s DPS calculator - http://druid.wikispaces.com/TosskDPSGearMethod
Rawr - http://www.codeplex.com/Rawr
Elitist Jerks druid forum - http://elitistjerks.com/f73/
MaxDPS is absolutely terrible for feral druids, as it still uses mechanics from level 70.

Feral druids use “rogue gear” - leather with agility and attack power as the primary stats. While the itemization is not “ideal”, that’s not actually important - what’s important is whether we can USE the available gear well enough to be as effective as other classes, and the answer to that is yes.

Stats
Agility - Our best DPS stat by a whisker in 3.1 as long as you have raid buffs and a high level of gear. At worst it’s only a hair behind, and can still be used for tanking as well. It’s the stat you’ll find most on gear, and the stat you’ll want to gem and enchant for in most cases. Caveat: See Armor Penetration

Strength - Strength drops somewhat in 3.1 relative to other stats - essentially equal to agility now thanks to primal gore. Since it does not appear on leather gear and we can gem for either strength or agility (and agility has a *slight* edge in raid buffs, plus can be used for tanking as well), the only place you might find it is on accessories such as rings, and on a few weapons.

Armor Penetration rating - Armor penetration was buffed by about 25% in 3.1, however it also gained a penalty to the amount of armor it reduces (the dreaded Blizzard “up to” in its tooltip). At 100% armor penetration, you are not actually reducing 100% of a raid boss’s armor. It becomes the best DPS stat if you have enough of it - the models disagree, but it’s somewhere between 250 and 450 plus a Grim Toll. Since it stacks with itself, if you don’t have much it is worse than strength and agility, if you have a ton it becomes very good. In 3.1.2, armor penetration was capped at 100%.

Hit - Hit rating gets passed by almost all other stats, even perhaps haste rating at some gear levels according to calculators. It should not be gemmed for, although it is still useful to have a reasonable amount on gear to smooth your cycles.

Expertise - Expertise has exactly the same effect (reducing the number of attacks that fail to land) as hit, and the same conversion, and so it has exactly the same DPS value up to the dodge cap. If you’re the sort that obsessively hit caps, don’t forget to expertise cap too.

Crit rating - Increased in usefulness thanks to Primal Gore, crit rating now comes in a little better than hit/expertise and haste.

Haste rating - Despite a buff to the stat, other feral changes mean it’s still one of the worst stats for us. It increases white damage only, which for ferals is less than a third of total damage. However, it also increases the number of procs from both Omen of Clarity and weapon enchants like Berserking and Mongoose. Mathematically it can exceed hit just slightly in 25-man raid gear, but hit makes cycles easier, and so is still preferable if you have to choose between them. Attack speed is calculated as 1 / (1 + haste%/100). e.g. with 9% haste, your attack speed is 1 / 1.09 = 0.917. Yes, ferals can attack more than once per second.

Stat conversions
1 Strength = 2 AP (2.38 AP with talents and full raid buffs)
1 Agility = 1 AP + 0.012% crit (1.19 AP + 0.014% crit with talents and full raid buffs)
1% hit = 32.79 hit rating
1% -dodge = 4 expertise = 32.79 expertise rating (8.2 rating per 1 expertise)
1% crit = 83.3 agility = 45.91 crit rating
1% haste = 25.22 haste rating
1% armor penetration = 12.23 armor penetration rating (actual penetration depends on target’s armor)

Gems
Meta: Relentless Earthsiege Diamond (+21 agility/3% critical damage)
Red: Bold (strength) or Delicate (agility), later Fractured (ArP)
Yellow: Inscribed (strength/crit rating) or Deadly (agility/crit rating)
Blue: Sovereign (strength/stamina) or Shifting (agility/stamina), later Puissant (ArP/stamina)
Prismatic: Enchanted Tear (+6 all stats)
Strength and agility are very similar in DPS value. The choice of which to socket is based primarily on your gear’s quality, your group buffs, and preference. A 25-man raider will probably get a little more from agility because of buffs. Someone in primarily heroics might make more use of strength. But a piece of gear socketed for agility also works very well for tanking, so dual-purpose usage might be a deciding factor.

Unless a piece of gear has a particularly good socket bonus, it’s best to primarily socket pure Bold/Delicate gems, and use either one Enchanted Tear or one each Inscribed/Deadly and Sovereign/Shifting gems to activate the meta. If your gear is gemmed for strength from before 3.1, feel free to keep your current gems until you upgrade your gear, as the DPS difference will be almost unnoticeable.

The only options for Armor Penetration gems, should you reach a gear level where that is the stat to use, are Fractured (red, pure ArP) and Puissant (purple, ArP/Stam).

Enchants
Helm: Arcanum of Torment (Knights of the Ebon Blade Revered)
Shoulders: Lesser/Greater Inscription of the Axe (Sons of Hodir Honored/Exalted)
Cloak: Superior (+16) or Major (+22) Agility
Chest: Super (+8) or Powerful (+10) Stats
Bracers: Striking (+38 AP) or Greater Assault (+50 AP)
Gloves: Major Agility (+20 agility) or Crusher (+44 AP)
Legs: Nerubian (+55 AP/15 Crit) or Icescale (+75 AP/22 crit) Leg Armor
Boots: Icewalker (+12 hit/crit rating) if not hit capped, or Superior Agility (+16)
Weapon: Massacre (+110 AP), Berserking (Proc: +400 AP for 15s), or Mongoose (Proc: +120 agility/2% haste)

The Hit Cap And You
One of the biggest falsehoods that gets perpetrated on the druid forums is that the first thing you should do is stack hit to the cap. This is not exactly true.

Feral druids do not suffer a huge penalty from misses or dodged attacks in PVE DPS. Our white damage is a modest portion of our DPS compared to most classes, and we don’t have damaging procs like rogues’ poisons or DK’s Blood-Caked Blade. Our missed specials only cost 20% energy. We are not GCD-limited or on a fixed rotation, so we don’t lose much time. Mathematically, hit and expertise rating are simply not as good, point-for-point, as agility.

This doesn’t mean that hit rating is bad. Hitting more often DOES increase DPS reasonably well. Reducing misses smooths your cycle out, allowing you to pay less attention to whether or not your last attack connected, which makes DPS easier. It simply means that if you have a choice between exactly-equal amounts of hit rating and agility, you should probably take the agility.

Set bonuses
Tier 6 2-piece - Reduces cost of Mangle by 5. A minor DPS increase (less than 1%), except in the particular case of a Manglespam build, for which it is essential.

Tier 6 4-piece - Increases Rip damage by 15%. This is the best DPS set bonus available, at around around a 2.5% total increase. If you can achieve it without sacrificing too many stats (particularly if you have the three Sunwell pieces of tier 6), it will last quite a distance into Naxx25 before it’s replaced.

Tier 7 2-piece - Increases the duration of Rip by 4 seconds. This is a decent set bonus (around 1-1.5% dps increase) that you should strive to achieve early on. It extends your Rip to 20 seconds in conjunction with the Glyph of Rip, allowing plenty of time to build combo points, refresh other timers, and perhaps even squeeze in a Ferocious Bite in between Rips. Keep this set bonus until you can get 4T8.

Tier 7 4-piece - Decreases the cooldown of Tiger’s Fury by 3 seconds. This essentially increases the energy from Tiger’s Fury over the course of a fight by 10%, which turns out to be a 1.6% increase in total energy regeneration. As approximately two thirds of your damage is yellow damage, this is about a 1% increase in total DPS.

Tier 8 2-piece: Allows Rake and Rip ticks to proc Clearcasting. According to Rawr, this is a pretty strong set bonus, but not vital. Definitely break 4T7 for it, but try to keep 2T7.

Tier 8 4-piece: Increases the duration of Savage Roar by 8 seconds. Most models are now predicting that 4T8 is going to be the way to go eventually, but I haven’t got round to looking at its actual value myself yet.