I've been running these numbers for a long time now. Guild Wars 2 has been particularly challenging for two reasons. 1) No one has really figured out the damage formula. 2) Every skill has its own scaling factor. And while the factor is linear, some skills will fair better from Power while some won't. So numbers are easier to crunch for one skill, but it gets tedious for all of them.
I've been running off a damage formula that I believe is correct. It only computes raw damage and does not take into account Armor/Toughness or glancing blows and misses. It is simply "How much damage will a hit do on zero armor?"
At its most simplest form it is:
(Attack)(Scale)(1 - Crit % + (1.5 + Crit Damage) ( Crit %))
SAI, a member of my guild, Gaiscioch, plugged this formula into a gradient vector. Gradient vectors are basically used to measure rate of growth of each variable in a formula. We can use this to compare growth between Power, Precision, and Crit Damage and decide which one to add to most increase our damage. Pretty cool.
Here's a spreadsheet where you can plug in different values. You can either choose different armor or just type your values directly in on the Total row.
The armor sets in there are PvE/WvW armor so they have stats built right on. For sPvP, it's easier to enter your own values and see what you need. Then go get the runes and amulet to match.
What does is mean?
This is only useful for direct damage builds, as condition damage uses its own stats and mixing them will actually end up making your build worse. But if you are going for direct damage, we can find points along the way where it makes sense to choose stats.
For example, Power is always the most important until you hit 1326 Power. This isn't a lot of Power but it's worth noting that even if you are going for a Crit build, you need this level of Power.
And even more useful, Precision is still the worst stat to increase until you add at least 36 crit damage. At that point if you add just 10 Precision, you can see crit damage important rise to the top again. So basically, stack crit damage. Once you hit 1326, stack crit damage. Of course at this point, I only know how to get to 40 crit damage, at least for an engineer. (Rune of Air, Golemancer, or Rage and +30 from Tools)
So if you're going for a crit build, get 1326 Power and 40 crit damage before you even look at Precision. Then Precision is your best bet until the end.
What's wrong with this?
It's boring. Now I have numbers that are pretty much set for a direct damage build. Good thing I like condition damage so much!