What are the qualities or attributes you most want a player in your campaign to have? What's most important to you from them?

Creativity and drive.

To accept victory and defeat, and treat those two imposters the same.

Enthusiasm and imagination.

Interest in the game, a willingness to roll with whatever comes up, and a good sense of humor.

The sense of humor is the most important.

Already be one of my friends.

"Mad charop skillz," said no DM ever.

I think the single most attractive feature a player can have for me, at least at this moment, is being open in regard to the future/arc of their characters.

1. Be someone I'm comfortable inviting into my home. Ideally, a friend.

2. Be interested in the game at hand.

3. Be a minimally decent and sociable human being, i.e. not an asshole.

I'm really interested in the flip side of this question as well.

A... fantastic cook?

Anyway you know the Dan Savage bit about being good, giving, and game? That also applies to tabletop roleplayers. With regards to roleplaying. At the table. With dice. Oh forget it.

I'd also add that being a player who can actively decide what he wants to go and do in the game, as opposed to sitting around waiting for others to decide what to do, or waiting for the GM do things to his character – this is an important quality. No good having a table full of people who can't ever decide where they want to go for lunch.

boobs

Being a decent, functional human being is not something I look for in a player, because it's assumed this will be the case if I associate with you. I don't have any dysfunctional weirdos who don't understand basic social interaction in any of my social circles.

So what I look for is commitment to showing up on time to every session (or the courtesy to let everyone know in advance if they can't make it) and engagement with the premise of the game (meaning you actually give a shit about it and want to get involved in what's happening).

What I don't want are casual tag-alongs who are only there because they lack any alternative means of socialising with other people. If your primary motivation isn't to play the game, spare us all and find some other way to spend time with your friends rather than hijacking the game session.

A compatible sense of what constitutes fun.  This is evident by the end of the first session playing together.

If the new person isn't having fun, no problem, thanks for visiting, see you around.

Imagination to have ideas, make decisions and plans on her own. Contributes to discussion when plans and ideas are exchanged. Willing to speak when her character should to something. A good player is thus socially active and contributes to team effort when necessary.

Human female genetic make-up and a nice figure (boobs are not enough) !

More seriously, I expect from the players of the game that I run a willingness to listen to the things I say as a GM and to have fun with the game which we are all playing.