First off, ignore Spirit. That's for the classes lucky enough to enable spirit mana regen while casting (priests and druids), a luxury we don't have. As a result, we're almost always within the 5-second rule wasting those spirit stat points.
For PvE, it's something like +healing > m/5 > INT > STA.
The key stats are +healing and m/5, with a conversion ratio of about +9 healing worth about +1 mana/5. That's a very rough number though, as some fights will require more of one or the other; LHW fights prefer +m/5 while Chain Heal spams do best with more +healing, for instance. You may want to start collecting 2 partial-sets of resto gear: 1 for regen and 1 for burst.
Intellect actually loses in priority as you progress, so is harder to quantify. For a standard 5-minute fight, 3-4 INT is worth about 1 m/5, but those numbers are also a little misleading. Heroics are more about burst healing--for which you'll want +heal and INT. However, raiding shifts the emphasis to longevity: a smaller mana pool and decent m/5 will get you much further than a stacked mana pool without regen. "OOM" acts like an enrage timer; to continue the metaphore, INT will make for a longer clock, but m/5 adds time to the clock during the fight. The longer the fight, the more m/5 is worth over INT.
As for stamina, I don't even prioritize it anymore since it always seems to be on the gear in appropiate amounts anyway. When comparing pieces, I rarely see STA off by more than a few points, which I only use as a tie-breaker. "As needed" would be the best description.
PvP is a whole different ball game, of course. I like resilience > STA > +heal > INT > m/5 > +spell crit, but I'm certainly no expert (my 5v5 finally cracked 1600 last night! Woo!!)