Purely speculation, but I'd almost say the newest PvP epics for the stamina and armor. The stamina is not so much for the Hunter, but for the spillover to your pet. After you spec max Fire Resistance and Natural Armor, there really aren't a lot of points left to boost your pet's stamina to any significant degree, since you'll probably be wanting Rank 2 Avoidance and your standard array of dps/threat generating skills as well.
In addition, anything that builds armor value on your Hunter (armor, agility, etc.) that would augment your pet's armor probably wouldn't hurt. Most Hunters would build for a lot of Agi anyways (for the AP) but it shouldn't be overlooked as something that also increases your armor rating which spills over to your pet. Just as with Stamina, the spillover isn't likely to be a huge number, but everything helps.
As you probably already know, pet armor scales semi-decently in Outland (my Boar had just over 13k armor the last I looked). It's the HP that gets you (I think Piggles has just shy of 6k HP). Since pets don't get the benefit of resilience (that I know of), it would likely be the crushing blows/crits that would put your pet in jeopardy.
Since I wasn't around pre-BC, I have no idea what a solidly raid-equipped level 60 tank might be sporting for armor rating in a fight like that. I'd be interested to see what the armor/HP of a 70 Hunter's pet would be if that Hunter was head-to-toe in Merciless Gladiator gear.
Beyond that, your guess is as good as mine lol
Edited, Aug 23rd 2007 6:42:14pm by AureliusSir