Actually, the dodge proc, Evasion, from the Triumph Libram procs just about any time I use Hammer of the Righteous. And even if it doesn't proc that one time, I've still got plenty of time left from the previous proc (I believe it goes for 20 seconds) that it'll overlap. Overall, I say the Triumph Libram is the way to go.

thing is, it isn't block rating, which helps you block more frequently, but block value, which helps you have bigger blocks when you do block. To that end, I don't really like the libram of the sacred shield. with blocking in general, either a hit is large enough to make blocking it basically irrelevant, or else the hits tend to be weak enough that blocking the little bit they deal also won't be worth it.

it's probably an awesome libram for soloing old world content before cata, where blocks can trivialize the weak hits, but i'd still prefer dodge for heroics, unless really gearing for block.

If you want threat in heroics (and if you're in the triumph emblem gear then threat is going to be far more useful than some extra avoidance) then use the 245 strength libram, as +200 strength is far better than some extra block. The only time to use the block libram is when you are running through trash and using Seal of Command (because the 245 strenght libram only procs off Seal of Corruption). For progression content, such as raids and possibly heroic Halls of Reflection (if your healer is undergeared) then the 245 dodge libram is the way to go.
I have all 3 librams and have them macro'd to equip when I use the appropriate seal. I also have the 226 divine storm libram to use when while Ret and running Seal of Command.

All excellent points. Librams are one of those key slots where you think about what you want instead of just going higher ilevel.

The only reason I would get the Frost Libram is for gearscore, because we all know that's what the game is about these days. However, I'm not going to give up something I prefer for gearscore. Especially because the difference is not that big between the Triumph Libram and the Frost one. However, my first purchase with my Frost badges is going to be the trinket because I'm still using The Black Heart from regular ToC (which I love) and Essence of Gossamer, because obviously that's a HUGE upgrade from the Essence.

My armory link: http://www.wowarmory.com/character-sheet.xml?r=Stormreaver&cn=Prot%C3%A9go

As others have mentioned before me, the triumph libram gives you a constant 200 dodge rating as it will proc every time you use HotR, and it is thus far superior to the conquest libram. The Frost libram is an EXTREMELY marginal upgrade to the triumph libram, and is situationally worse as if your stack drops off it'll take you three rotations as opposed to one to get the buff back to beating the triumph libram - thus it is generally recommended to get everything you can with frost badges before picking up the Libram of the Eternal Tower (even your ret offset).