Well, my priest is only 19 at the moment but after looking through all attainable gear for her up to 55, I'm choosing to prioritize like this:
1) INT
2) STA
3) everything else
My reasoning is simple. I don't have to worry about Spirit because it's tacked on to seemingly every piece of decent gear from say, level 26 on up. Therefore, I don't have to actively seek it out (and possibly sacrifice a better/more useful stat like stamina). I use the same strategy on my Mage as well. Survivability is a paramount concern only surpassed by mana pool. When some Defias Overseer or somebody comes over to smack me while fade is recharging, I'd prefer to be able to take the blow without wilting or flinching. Besides that, all the tests on the effect of Spirit (look
here for one of them) have led me to believe it's not worth worrying about, honestly. Cost:benefit ratio is WAY off.
Just my view though.