I'm not exactly sure about this.. but since no one has responded yet, here goes a starter discussion post (prolly build from there).
Pre-Outland gear your main stats to get for tanking is Str/Stamina. Agi is always a bonus, but I'll take "...of the Bear" over "...of the tiger" anyday.
Agi, boost your armor a slight bit, improves your crit rating a slight bit, and increases your dodge rating a bit (per kara list sticky). Which is great if you can sacrifice one of the tanking stats (str/stam).
I'd suggest if you're DPS'ing and don't really need a whooping load of stamina or strength... and can even out the Str, Stam, Agi ratio, then go for it. There are items that will give you all 3 stats, those are great.
Post Outland, you really seperate your two sets (dps & tanking), until then go with w/e you can get a hold of that does not set you back too far time wise.
Edited, Nov 1st 2007 2:55pm by GYFFORD