Okay, here's a chance to voice your opinion over what you feel is the most important player trait.
Only list ONE. I know that there are a multitude that make a great player, but in your eyes what's the one thing that separates "a good" player from a "great" player?
Obviously, I'll go first.
* Able to succeed outside of the formula. We spend countless hours trying to find the most efficient way to complete a quest. Then we develop a formula. This is especially true of raids. However, in my opinion the best players are the ones that can still succeed at that quest outside of the formula.
For example. Said quest needs 2 clerics, 2 melee, a bard, and a caster. However, can you still complete quest if one tank is swapped out for a rogue, etc?
Also, when the formula breaks down, can you recuperate without going into a tailspin of frustration and anger? Can you recuperate at all?
I'll sum up the above in one word - "Flexibility"