If you are talking about for selling then all the main attribute ones. Willpower, strength etc
If your talking about for yourself. Then go for as much Power as you can. You will find by the time you are 50 and have most of the operation gear that you have maxed out your main stat and everytime you add to it the returns diminish. Power is not capped, so if you are like me and are playing a Inquistitor you will swap out all your Willpower/endurance augments for Power/endurance onces for added DPS.
If you want to be playing suboptimally then yes, use the power ones. For pretty much all DPS and healers you want to use the main attribute augments, which is why they sell the best. Diminishing returns for your main stat don't start really hitting hard currently until somewhere around 6000, so at that point the power augments would be better, but since it's impossible with current gear to get even halfway to that point stacking your main stat with augments is optimal for DPS and healers.