Lots of great responses I agree with.
Sense of humour definitely.
Also find intelligence in a woman sexy, and not being afraid to be intelligent. Doesn't mean the lady has to act like an arrogant know-it-all, but a well thought out opinion, a confidence that whether she is right or. It she wants to share an insight.
Often find that intelligent women have the best sense of humour too because the funny comments are on a different level, and not everyone in the rooms gets them.
From a physical feature perspective, it's always always the eyes and smile. They say so much, and can be fun, naughty, friendly, smart, kind and so much more all at once.