Okay, first, my bad. I meant to put Elder haha. I'll change that. Second, this is my argument for spirit vs crit.
First, crit has two functions. It either a) helps healing throughput, b) helps DPS throughput. We can ignore healing throughput off the bat. Here's the reason why. Lets say you are healing someone. The chances are high that you are going only be weaving one heal in between a shield. In other words, if someone is at 600 HP, you are going to be healing once, then shielding for proper disc play. That means that you only need to heal about 400-500 health. If you crit a flash heal, or 2 tick penance (assuming you are faking the third or clipping it).. you are likely to hit really close to 700. If you don't you are hitting around 360 (this can be verified from multiple sources). That means on average, you are overhealing by around 200 health. That means you can trade some of your throughput out for other stats. In this case, that stat is spirit. So we should all be able to agree, that for healing sake, you should prioritize spirit.
That means we have to move on to DPS. YES, crit is really nice for DPS. I completely understand that. The problem is that you are not trading away enough crit for it to make a difference. At best your gear set difference will amount to something like 2% more crit. 2% more crit does NOT make the difference in burst in this bracket. This is the exact same reason that people do not gem crit (preferring haste) in end game. Crit is very nice, but until you get it to be a reliable source of pressure (at end game 30% for fire was about where I was in s8) it's not a good source of damage.
Lets take arena. You crit 15% of the time. That means on average, if you crit, you did put out more pressure but you are not reyling on it to win games. In other words, if you are playing a mirror RMP, the priest that crits first does not score a kill. If you can't rely on getting those crits (in other words proc'ing pyros in end game and chaining said burst into combustion) you should not be relying on crit as your secondary source. Spirit is far more beneficial because at the end of the day you can still get the same kills without relying on crit making it not as valuable. I just can't justify going for crit when at best it's only use is for two spells (Holy Fire and Mind Blast). Everything else, spirit is king.
Also, I don't know how you guys play priest, but my uber-offensive style ran me down on mana pretty quickly since I was using every other global offensively.