The politically correct answer is of course 'love'.
But sadly, from what I've observed, pretty girls and handsome guys
get attached more easy, and more often. Some people even look at
chio bu/yan dao and claim that they've fallen in love with that
person 'on first sight'. I don't believe in this.
And just look at friendster accounts. Chio bu can easily get up to
more than 500 'friends', while the plain looking ones can't even
get 100.
The not-so-good looking ones will remain unattached, even if they
may have a good character.
For me personally, I'll go for love. I'll not go for looks, but
more for character in my girl. And I'm saying this not because it's
the politically correct answer to say, but because sometime, beauty
is really skin-deep. And they don't last, at all.
At the end of the day, you'll find that it's often the girl with
good upbringing, good character and loyalty who'll stick with you
till the end, not the stunningly beautiful one who can easily dump
you for another guy when a crisis strucks.
I have male friends who certainly look very handsome. And girls
always fall for them. But their character sucks, and they change
their girlfriend as often as they change their underwear.
Sad to say, I'm not very good looking myself, so I'm still
unattached 
