I've had a few debates with fellow ret pallys on what stat is point for point "better" for a ret pally, agi/crit rating or haste. Now I know its gear dependent, and everyone's item weights are going to be slightly different, but my intuition is telling me the crit is better, and while pondering this question at work today I've come to a few assumptions:
Haste is good for a ret pally for a few reasons: increased melee strikes and thus more seal damage, as well as a greater chance for divine storm CD to proc through these increased melee strikes (this is theoretically a dps increase). But at the same time, doesn't the human error in not hitting divine storm every time it comes off cd instantly take away from that benefit? Even though your still benefiting from that haste in regards to your weapon swinging faster, your not getting as many actual divine storm uses per fight as a simulator would say you are. Not to mention the fact that sometimes mana is an issue for us now. So even if you are getting every divine storm when it pops off cooldown, which is difficult but by no means impossible, you run the risk of going OOM through these increased DS uses, or have to blow a gcd on a divine plea. And how many times has DS came off CD during the middle of a GCD? nearly every time, and if it doesn't, you probably miss it 9/10 times because your already spamming another ability.
Next is my reasoning is why crit/agi is a better stat than haste. It has to do with ret paladin mechanics and how they interact with the ICC buff.
If I'm assuming correctly, the increased damage ICC buff is applied per spell usage. For example, you use judgement of vengeance on a mob, the game takes your stats at that very moment as well as other factors such as mob debuffs and talents and calculates the amount of damage that spell does, then just multiplies that number times 1.x, with x being the ICC buff level we are at right now.
So lets say your judgment would normally hit for 10k crit on a mob with no ICC buff. With the current buff level of 10%, it would be displayed as 11k, a 10% total damage increase. But since it was a crit, righteous vengance comes into play, and with RV comes another strange ret mechanic with the crusade talent and undead mobs.
With no ICC buff that 10k crit would place a righteous vengeance debuff on the mob that would do a suspected total of 3k damage. But with the crusade talent (4% more damage to undead and other types of mobs) that 3k total dot is increased to 3120 damage. So your total damage done by a judgment crit is 13120.
With the ICC buff that 10k crit is going to be bumped up to 11k. The RV DoT total would be 3300 (the 30% of the initial crit) multiplied by 1.1 (the current ICC buff as of 3/30) multiplied by 1.04 (crusade talent), totaling 3775.2, bringing the final damage done by that judgment to 14775.2
14775.2 divided by 13120 = ~1.1262, a 12.62 total increase to judgment, DS and CS crits. This is the reason why I believe crit is either superior to now or will overtake haste (as the ICC buff increases) in terms of point for point itemization. Now I know I haven't taken everything into account. There are about a million little factors you could throw into the eqaution, and how that specific equation actually translates into specific boss fights in ICC is extremely hard to calculate and I just don't have the time to do it. But my gut feeling tells me that the absolute passive benefits to crit and agi outweigh the benefits that added haste brings to a ret pallys rotation and damage.
I'd like to hear what the ret pally community has to say about this. Remember, this is just my opinion supported loosely with some numbers. By no means am I saying that hands down I'm right. I'd hope to see some more numbers in your arguments too and what you have to say on the situation. And remember...
[size=10pt][size=10pt][size=10pt]ROLL DAT FACE BABY[/size][/size][/size]