My general commendation priority. It's not required to do both but if I notice either I'll take note. It's not in a specific order...

1. Melee using fient + LB only on last boss (ideally a range should be lbing but people hardly LB)
2. Phys Range using their mitigations + LB on mob packs
3. Caster using addle + LB on mob packs
4. Tank not pulling raw
5. Not spamming cure 1/benefic 1 + aoeing

Alot of people commend based on your portrait though. I don't think many put much thought in it, some don't commend at all and just leave immediately.

Ironically I got most of my commendations on BLM. I guess people are super impressed by aetherial manipulation and not eating stacks for days plus LBing big packs of mobs.