I comm DPS second most after healers. I comm tanks the least, because I usually am the tank.

But even when I'm not, most folks who play tank do a very poor job at it, and this has been consistent across expansions. There's only been a few dozen times now in thousands of dungeon runs where tanks did well enough that I commend them.

Healers get my comm more often than not, because they're the only role where other people playing badly makes them have to do more work. More often than not, healers in XIV will put in that extra work to help those bad players out. I notice that, so healers usually get the most.

So basically I comm DPS when healer is very very bad or very very snobby. Or when the healer leaves too quickly. I won't comm DPS though if they played really poorly. No/few AOEs or AOEs on boss when there's no adds. I've seen some DPS do some pretty whacky stuff.

Though if there's a female Roegadyn, Elezen, or Highlander in the party and they are decent they usually supersede my role rules. Make my heart go doki doki, and I'll comm you. I'm weak.