[i]What came first, the chicken or the egg?[/i]
If you play as a team, you cannot have one without the other. Bottom line: killing more than you die = victory (not including weird game types). If you are playing a FPS, the goal is to kill more than be killed. Therefore, K/D cannot be ignored. Yes, you can be a good team player and bring more to the table than pure lethality, but kills win games and deaths lose games. There is a relationship here that cannot be ignored, so I don't understand why people keep asking this question, assuming one is better than the other.