I don't see why you would take Rams over Tier, the itemization on tier is obviously superior, with 10 more stam. Unless you think that 26 def and dodge aren't cancelled out by the parry the tier helm provides. Is it the fact is has hit? sure threat is important but the tps you get off the strength outweighs the hit.
As for tier debate: helm, chest and gloves are BiS at 277 because of the superior EH, bone pauldrons pulls ahead over tier shoulders but the 4p can be an effective situational use on any boss that hits hard, IE any of them in 25m heroic.
Too many of you seem to be argueing the importance of armor. YES it is worth than stam because it does not cover magic damage but bonus armor is a SECONDARY STAT. It competes with defr, dodge, parry, hit and expertise, and since there isn't a boss that uses 100% magical damage it's still amazing EH on all fights in ICC.
I do however dislike the fact that they've couple it with DP, the skill is used to control mana and a small dr if you glyph it; not avoidance. Sacred shield, Dsac or even if they made it salv but took of the penalty would of been a much greater option.
I'll update it with Gem choices and enchants sometime later, on holidays now so have plenty of time.
The reason we got avoidance with DP is frankly as a way to help scale the other tanks up a bit more to paladins. Lets face and admit it, based off talents abilities and glyphs we are the best tanks out there, thus blizzard realized it and gave the others a much better 4pc than us. However tying it into other smaller CDS it becomes a major allowing one extra soul reaper without an external being needed, or int he case of hallion it allows your trinkets and 4pc to make surviving the first 2-3 seconds in a new realm much easier on the healers.
As far as the armor to stam argument the math shown earlier is based off 100% physical dmg, no buffs, and no 25% icc buff, the line is much more blurred in ICC now as there are more choices where the extra stam on a 277 may outweigh the armor on a 264(cloak and belt).
I'll defend 2pcT10 bo0nus for paladins, it's great. I'd ensure to have at least those at all times.
As for armour, it's value increases as the buff increases. At current levels, I would do anything to get armor over stamina, but I'm an armor whore. Having said that, except for a few fights (Kiting Keleseth, Sindragosa, etc.) most encounters have both armor and magic components.