My vote goes to the person who is nice, says "hello" and "thx for group" at the end. Ones that don't complain and if the party wipes try to advice on how to change our strategy so that the fight becomes easier. The ones who advice the newbie players or the ones that try to make the dungeon a little bit less painful.

If I'm playing as a tank or healer I usually leave if there is a rude player in the party. I rather spend 15 minutes doing something in the house than helping a rude player get gear. If I'm playing as dps I usually play with my friends since I don't want to deal with rude tanks or healers, those are the worst IMO.

ps. OP is completely off the mark and is complaining about non-issues.