Guild Wars 2

Destruction of the Empowered – +3% dmg per boon on target
Attack of opportunity – +10% dmg on bleeding target
Armor Attack – 10% of toughness converted to power (250 – 300 power)

Can someone do the math on which one is better and when?

Armor attack if you stack toughness. IE Knights., Rabid, Soldiers…
Attack of Opportunity is great in general. You will create bleeds on your own or especially with a group, so it’s a staple 10% dmg bonus pretty much.
Destruction of Empowered is probably the worst of the three as it is situational. Terrible for PVE, it may have some use in pvp and especially wvw, as boon stacking is pretty common.

They all require you to spec into different trait lines, so I’d say it depends on what you want to be. You could probably grab both attack of opportunity and armor attack if you were a condition warrior using rabid armor. I prefer to only go 20 into defense for cleansing ire and dogged march but the buff to armored attack probably make it worth it to go all the way.

My main issue is +1% dmg = power/100 ?
If so then
power/10 > toughness/10 —> power > toughness, which is usually true.
So there is p<1 such that power*p = toughness
now need to add the situation percent, i.e: if target bleeds p2 percent of the time then
p2 > p1
anyhow…

According to the Wiki (“damage for weapon skills is based on the product of weapon strength and power”) I would say that +10% damage does the same as +10% power, so if power is higher than toughness it’s the better deal.