The first time I asked my guildies about how to gear my feral tank they gave me some straightforward advice. Just stack agility and the rest will take care of itself.
Not bad advice, but sub-optimal.
In 2009, feral tanks need more than avoidance to perform at the top of their game. Especially since diminishing returns on avoidance were confirmed in Wrath of the Lich King. I have since spent a lot of time crawling through posts by Ciderhelm and Corbusier on TankSpot & Elitist Jerks, and have come to trust their wisdom regarding Effective Health.
The combination of wit, mitigation, avoidance, and a nigh-insurmountable hit point total is something I call Leatherbelliness™. This is just a playful term I use to describe a large Effective Health combined with a smart play style and good technique.
I won't get into the nitty gritty just yet, but Effective Health works out like this: If you have 10k health but only get hit 65% of the time, you effectively have 15,385 health. If you can reduce 10% of the damage you do take after avoidance, this number becomes 17,094 effective health.
All tanking classes have effective health--death knights and paladins can self-heal, warriors can mitigate damage through massive absorption. Since WotLK does away with crushing blow mechanics, it might seem like having big EH isn't quite as important as it used to be.
Don't be fooled. At the end of the day you get to dine on knuckle sandwiches. Twitchy melee DPS who don't grok the parry mechanics and haven't capped their expertise can still put you on the wrong end of a haste debuff with a boss through bad placement, and when you're riding on 30 or 40,000 hit points your healer will appreciate the depth of that health pool, will perform fewer overheals, and your blood pressure will remain at optimal levels as a result.
Now, that said, Leatherbelliness™ is not a slave to statistical averages. From time to time, people will ask me whether a given piece of gear is "better" than another piece of gear for tanking. You've seen it in guild chat. You know what I'm talking about. My answer is consistent, one learned from my time as a software engineer.
It depends.
What's the situation? Every engineer knows that there's a tool for every job. Different jobs call for different tools. Is there one single set of gear that's going to be "best" for feral tanking?
Nope.
With that in mind, I go for maximal Effective Health on average, but I keep an arsenal of specialty options at my fingertips. Knowing when to ditch some health for dodge or increased threat generation, and being able to do so with one click because you came prepared, is Leatherbelliness™ at its best.
I learned to play WoW on a warrior, which taught me all about the importance of knowing what gear to use in which situation. For about six months I maintained custom gear swapping macros that were tuned to the stance I was in as a warrior. When I flipped into defensive stance, out came the shield, defense, and expertise gear. Those lessons carried over seamlessly when I started playing my feral druid (and started using Outfitter, thank the skies). To this day, when I switch into caster form, my mana pool explodes, cat form drops me into my strength, crit and AP gear, and when I go from either to Dire Bear form, it sets off alarms on my MikScrollingBattleText, because my max health in Cat Form is about 25% of my total when wearing my tanking kit in Dire Bear form.
This continues to freak out my healer, by the way.
In WoW, as much as anywhere, the clothes make the (man|bear|tank). So, my first piece of advice is to get big bags and the Outfitter addon. Especially while you're questing and leveling, you're going to need utility in cat and caster form. Having the flexibility to quickly swap gear will allow you to truly specialize for tanking while you are in Bear and Dire Bear form, instead of trying to find the one-size-fits-all gear set that just does not exist.
