This tweet by Morgan Allan Knutson sums it up perfectly for me. And if I need to put it into a single quality, I’d say that’s collaborativeness.

So far I’ve seen that designers who are collaborative are also:

Trustworthy
They are equally good at getting people to trust them, as well as trusting others.

Kind
Not just nice and smiling (rainbows & unicorns), but genuinely kind and honest to people they work with.

With lack of ego
In order to trust their collaborators, they need to respect them, but also loose their egos. This doesn’t mean to have no attitudes/opinions and not standing up for themselves.

Thank you Gary Goh for requesting this answer from me ✌️