Guild Wars 2

I asked me this questions and started a bit math and hoped to find a General question.
The answer is, there is no concrete answer for this Topic. Everyone has to calculate some formulas when he wants to know if Force or battle or maybe bloodlust is more effective for his build.

The General formula to see which dmg u inflict is:

Dmg done = Dmg Multiplier * (Weapon strength * Power * skill-specific coefficient / target’s Armor)

Dmg Multiplier: that Counts the 5% dmg from S.o.Force or trait effects like dmg Bonus on weapon sets. 5% dmg is a term of 1,05.
Weapon Strength: for this term u can take the average number from the dmg range of ur weapon, for example exotic Greatswords have a range from 995-1100. So the average is 1048.
Power: u can take this term from ur hero Panel, but dont Forget that Stacks of might increase this term. I advise to type ( power + 0) in ur calculator that u can easily Change the formula later.
ssc: each skill has a secret coefficient that converts ur power to dmg. U cant see them ingame, u Need to look for the Grey number in
http://wiki.guildwars2.com/wiki/Main_Page
just search ur skill, i recommend for first the autoattack of ur weapon set.
Targets armor: this term is not specific, i suggest to take the reference armor of the different classes:
Scholars: 1836 / Adventurer: 1980 / Soldiers: 2127

So when we just say sigil of strength gains us perma 3 stack might we have to add 105 Power to the formula.
for sigil of force we just Need to write 1.05 in dmg Multiplier.

Because of the dmg range the calculated numbers u get dont Need to be the same as ur ingame of the skillfact.

All in all to answer the above question, every build which focuses in Power as mainstat (armor, weapons, trinkets, traits) should use force
a bit “weaker” builds can use strenght for better dmg (condi dmg too)

For theorycrafter i can recommend These sites:
http://www.guildwars2guru.com/topic/60838-math-damage-reduction-toughness-and-vitality/
http://gw2buildcraft.com/articles/calculator-faq/

i hope it helped some People and i am open for improvements from better mathematics