Best overall: Durable Nerubhide Cape, a Leatherworking BoE.
Best drop: Because we do get the additional AC from this slot, Flowing Cloak of Command off Salramm the Fleshcrafter in normal Culling of Stratholme is technically best here. However, Cloak of the Gushing Wound off Erekem in heroic Violet Hold and Shroud of Reverberation off Volkhan in heroic Halls of Lightning are also surprisingly good, I think because of the meaty stamina allocation on both and the chance to get some +hit on the former and +expertise on the latter.
Best quest piece: Bloodbane's Resolve, from the quest The Fate of Bloodbane in Icecrown.
Best faction piece: Cloak of Peaceful Resolutions, available at honored with the Wyrmrest Accord.
Runner-up: Cloak of Tormented Skies, a Leatherworking BoE.
Enchant: Enchant Cloak - Major Agility.
Best overall: Heroes' Dreamwalker Raiments, available for 80 emblems of heroism.
Best drop: Crystal-Infused Tunic, off Keristrasza in heroic Nexus, or Drake-Rider's Tunic off Skadi the Ruthless in heroic Utgarde Pinnacle.
Best quest piece: Exotic Leather Tunic, from the quest Junk in My Trunk in Utgarde Pinnacle.
Best faction piece: Darkheart Chestguard, available at exalted with the Ebon Blade.
Runner-up: Much as it kills me (again) to have to write this, Savage Gladiator's Dragonhide Robes (available for 60,000 honor or 45 emblems of heroism) are extremely good, and are actually better than your options from quests, factions, and drops, but frankly you're better off saving emblems toward Dreamwalker.
Enchant: Enchant Chest - Powerful Stats is usually the way to go, but if you're hurting for stamina or just stacking the motherloving snot out of it for Sarth 3D, use a Heavy Borean Armor Kit.
Best overall and best drop: Bindings of the Tunneler, off Skarvald the Constructor in heroic Utgarde Keep. These are really excellent and not that far below drops in Naxx-25. Keep farming heroic UK until it drops. If it doesn't, you may want to try for some PvP bracers.
Best quest piece: Njorndar Furywraps, from the quest Not-So-Honorable Combat in Icecrown.
Best faction piece: Dragonfriend Bracers, available at exalted with the Wyrmrest Accord.
Runner-up: Drake-Champion's Bracers, a BoE trash drop in Oculus. If you don't see this on a run, keep checking the AH, but this is one of the tougher BoE's to get because Oculus is a fairly unpopular instance. Eviscerator's Bindings, a Leatherworking BoE, are fairly close to them in time-to-live calculations, however.
Enchant: Until the patch it was easily Enchant Bracer - Greater Stats or Enchant Bracer - Expertise. Now you'll almost certainly want Enchant Bracer - Major Stamina.
Best overall: Heroes' Dreamwalker Handgrips, available for 60 emblems of heroism.
Best drop: Charged-Bolt Grips, off Ionar in heroic Halls of Lightning, or Bile-Cured Gloves, off Meathook in heroic Culling of Stratholme (although if you're already doing CoT you should really just use the quest gloves).
Best quest piece: Handwraps of Preserved History, from the quest A Royal Escort in Culling of Stratholme. These got a heavy nerf recently and are no longer the best-in-slot item (yes, better than Tier 7.5) they were, but they're still pretty damn good.
Best faction piece: n/a.
Runner-up: The odds of this showing up on the AH are astronomically low, but check around for the Naxx-25 BoE Gloves of Fast Reactions.
Enchant: This is arguably the most customizable slot for enchants. Enchant Gloves -- Major Agility, Enchant Gloves -- Expertise, Enchant Gloves -- Precision, or a Heavy Borean Armor Kit are all possibilities here. While Major Agility is the best overall enchant for most bears, use Rawr to find out if one of the other options is better for your current gear set.