What about Endurance? If you play the role of a tank frequently, it may be in your better interest to raise Endurance as much as possible. However, you still should not neglect your class primary stat. You may notice a lot of gear that has Endurance listed as a higher number, such gear may be better for tanks. Even if you're not a tank and if survivability is quite important to you, then raising Endurance more may be a good idea for you.
Bounty Hunter (Mercenary/Powertech): Aim
Imperial Agent (Operative/Sniper): Cunning
Sith Inquisitor (Assassin/Sorcerer): Willpower
Sith Warrior (Juggernaut/Marauder): Strength
You got the "primary stat" right. However, endurance is the number 1 stat for any and all classes really (not just for tanks, as you say).
I play IA Operative. Cunning will make me do more damage, and it will make me heal more. But I can't do any damage if I'm dead, and I can't heal anything if I'm dead. So since endurance makes me not die, Endurance is the number 1 stat. Cunning is 2nd only.
For most people, the primary stat should be fairly obvious, since most of your quest gear is aimed towards this stat and also the PvP armor that is class specific etc. But nice of you to write a guide for those that didn't notice the hint.