Tbh, it all depends on any given situation for me, to know and react appropriately.
It's one thing if a guy is with his buddies, fraternity brothers, etc, and plays along with whatever is the topic of conversation, within reason and respectful boundaries to some degree.
Too quiet and not contributing to any conversation does get rather boring after awhile.
Too loud, too boastful, getting too drunk, losing control too often, definately not appealing as well.
A definite sense of humor, a respect for the company one is in, respectful honesty rather than bragging, a certain level of comparable intelligence, compassion for others- humans as well as animals (a BIG one for me), easy going, committed to one's beliefs but open to respecting other's beliefs and LISTENING.
Irregardless of personal physical qualities, I would have to go with compassion, self confidence but with an equal dose of humility, humor, reasonably comparable intelligence, and "fairly" similar political and religious views/tolerances but with an open mind to discussion without ridicule or excessive judgement.