What is your preference for a player to get a commendation?

[Jade_Roux]

My opinion is that Tanks and healers are key roles. A bad Tank can cause a wipeout as well as a bad healer. So my commendation always goes to a good tank or healer.

[Rahferu]

I try to give a comm every time I get involved with a duty if possible!
I give them based on how they did with their party role--regardless of what they're playing, and how they acted. Nice people doing good jobs deserve recognition, imo. Doesn't matter what class you are, as long as you're respectful and do your part as best as you can. Having a nice outfit is an insignificant bonus imo (seeing as glamour doesn't come until level 50 anyway) but honestly I'm going to be more prone to weighing your merit based on how you did and how you acted.
If someone's an unreasonable jerk then the odds are I'm going to ignore them, not give a comm and move on with my life (though I do try to give people fair treatment and the benefit of the doubt.)
As far as part performance goes, one has to bear in mind that supernew players run dungeons too. While it can be slow and sometimes a little frustrating to deal with depending on the situation, we all started somewhere. >.>

[Lunaxia]

I don't really have a default role I give comms to, it depends purely on how they played/ behaved. I can be quite stingy with comms so unless someone impressed me or really improved the run in some way, I won't always give them out.

Friendly/ helpful players will usually get one though, first and foremost. Healers who stance dance well too. Occasionally the tank if the dungeon is well-paced and feels seamless, and they don't give me a lot of work to do. I do keep a special eye out for DPS, because they can definitely be the unsung heroes - I gave one to an amazing MCH yesterday who completely annihilated the mobs and got us to Hraes in 20 minutes despite practically carrying the BRD damage-wise.

But it's ultimately behaviour > performance. I can comm a guy who was chatty and friendly even if he didn't play all that well, but I will never comm someone who was great at their job but acted like an ass.

[Chalbee]

I give it to whomever has earned it, and it really varies by role, job, and duty. A summoner slinging DoTs around like a pro will always get my comm over a White Mage who is just there existing. I understand the impulse to give healers all the comms, and I probably give a plurality of my comms to healers anyway, but they need the Tank/DPS as much as the Tank/DPS need them, so they still have to show some effort.