You'll need a bit of experience to properly judge an item's worth in conjunction with your current gear, I'll give you that. But no mathematical formulae can replace that experience. If you don't learn to judge it by your experience, you 'll be pretty much lost.
F.e. this cloak is generally considered very powerful:
I usually use this one instead:
I wouldn't have thought about using the latter over the former during ROK since I lacked heal crit. Now that I have 100% heal crit, I use the former as dps cloak, and the latter for heavy duty healing. I dont think you can come up with a formulae for this, and an ordered list will fail as well. Add to that the extremely situational use for either power procs, CC immunity, dps gear, ...
Just for the luls and since no groups are going today, I'll try and make a generic list for a templar who has to heal... (I had to add a few stats)
+base heal
+heal crit mod
Wards per minute (single target)
10% to next heal (if it wasnt bugged)
Reuse
+heal crit
Cast Speed
Power per minute
HP per minute - Ring of Forgiveness = 700x4 = 2800
WIS (for templar mythical buff to reactives)
Crit Mit
Heal Amount Mod
Double attack / Melee Crit Bonus / DPS Mod /Haste
Resists / HP / Power / INT / STR / STA / AGI