I don't really have criteria that affects my decision on whom to give the commendation to. It's fairly random. Though I will often give it to the other DPS class. But if anyone acts like a total jackwagon, no matter how well they performed, they will NOT be getting my vote. I will also give my vote to new tanks and healers, especially if they did pretty good on their first time. But if everyone did a great job, and it was enjoyable, I'm often conflicted who to vote for (though I'll side with the other DPS class). Some times I wish I could give everyone in my group a commendation.