Re: 75/50 Stam Gone, now what? (Can we have a long discussion on best enchant?)
Like you, I understand fully why it didn't make it to the live realms. I am kinda annoyed though that they didn't make another viable option at this time, although I hope it will be coming soon.
As far as your question goes, I'm not too sure. I personally have +26 agi on my weapon atm, but I'm a warrior and I dunno if there are any major differences regarding pala tanking. The hit/crit enchant you describe is Enchant Weapon - Accuracy (http://www.wowhead.com/?item=44496), beats titanium weapon chain as far as I'm concerned.
+26 agi leans more towards avoidance, while the +20 strength or +65 AP leans more to threat generation.