As I was reading everyone else's posts, my mind wandered around to my own experiences, and I had a thought about some of the lists of qualities I saw.
If a diver has almost all the qualities on one of those lists, that diver might not be, in my view, a better diver than someone else who has far fewer of those qualities.
The worst dive buddy I ever had was someone who had the entire boat load of divers on a week-long liveaboard fully PO'd. He was a very experienced diver with excellent skills. He really had only one real problem--he was so thoroughly wrapped up with his own personal needs as a photographer that he really didn't give a damn about anyone else. He would nearly shove people out of the way to get into photographic position and then stay there with his super-sized memory card slowly filling. While we were buddied (which was not for long), I could have drowned and he would not have known about it. Out of the water, he was a very friendly, personable, and helpful guy. In the water, though....
That one defect outweighed all of his other skills and characteristics.
I am sure that there are other defects that can counterbalance a pile of virtues.