I went through this very informative thread here...
... and did some serious number crunching to come up with general rules of thumb for stat priorities.
These rules apply to all classes. SWTOR has a nice scaling system which ensures that the damage of all skills scales equally. This makes theorycrating much easier. I won't go into detail about my calculations because they are very complicated and require much space. But here are my rules of thumb.
For PvE I considered maximum average DPS as the priority. The result here is that your absolutely best stat is Power. Power has a greater benefit than your main stat (Willpower, Strength, ... etc.) in ALL cases. The small crit bonus of the main stat doesn't make up for the difference in raw base damage. Also both Power and your main stat are ALWAYS better than any of the secondary stats. (actually the secondary stats become better at some point, but this point is far beyond realistical stat levels). The priorities are as follows:
- Power is always your best stat. Take it anytime you can
- Willpower/Aim/Cunning/Strength is always your second best stat. Take it anytime Power is not available
The secondary stats have varying prorities depending on other stat levels:
- Accuracy is initially your third best stat until you reach around 413 (~102% hit chance)
- After that, crit rating and accuracy are about equally good until you reach around 70 crit rating (~3% crit chance) and 500 accuracy (~104% hit chance)
- After that, surge rating and crit rating are about equally good until you reach 100 surge rating (~67% crit bonus damage) and 230 crit rating (~8.8% crit chance)
- After that, crit rating, surge rating, and accuracy are about equal until you reach the accuracy cap at about 890 accuracy (110% hit chance)
- After that, crit rating and surge rating are about equally good
In PvP some different rules apply. Burst damage is more valuable here than sustained dps. Also, there is expertise, increasing offense AND defense. Additionally, accuracy over 100% is often not worth it because not every class has 10% defense. So for PvP, only a few hints:
Conclusion and simplification
- Power and main stat are still your best offensive stats (much better than expertise offensive wise) and are imo worth taking even over expertise
- There is a sweet spot for surge rating around 100 (67%) where power and main stat surpass surge rating in benefit for your crit damage
- crit rating might be more valuable offensive wise, this is according to personal taste of finding the burst/sustained damage balance
- General rule of thumb: raise power/main stat as much as you can, get accuracy to 100%, surge to 67%, then stack expertise. Add crit rating according to personal taste
There are some other influences to the stats presented here of course. For example you talents that raise surge/crit rating of certain spells, which can change the balance here. But at least with the obtainable stat levels now, even with talents, the secondary stats won't surpass power/main stat in value.
I don't know exactly how the talents stack with your base values, but I do think that they are just added after the other calculations, which means the rules of thumb above still apply basically, so if you have +3% hit chance via talents you would still go to 413 accuracy (total of 105% hit chance) before raising the other stats. Of course you wil stop raising accuracy when reaching 107%.
Additionally, many classes have talents that proc on crits or talents that raise the crit chance of a spell to 100%. The first talent type increases the value of crit while the second one decreases it.
Also, there are talents like +6% willpower, which of course, can increase the value of the main stat to a level that it is better than power.
To provide a more simple rule of thumb which might not be that optimal but more easy to remember:
- Put everything you can into Power or main stat
- Raise accuracy to 100% including talents
- After that, do what you like most