Ret pally back enchant

[Tandel]

What should i enchant for the 23 haste or the agi enchant

[Martie]

I'm gonna say it matters very little, both are suboptimal threat stats. Come to think of it, it may even depend on your gear, since haste grows in value faster with good gear then crit does.
Agi should be slightly better at most gear levels, with haste getting closer to agi's value as your gear gets better.