(1) Genuine ethnic diversity (simply unmatched in its breadth and scale), and a genuine, bedrock belief that (at least in principle) if you're a citizen you have a right to be here and to live your own life, dammit whatever your ancestry, religious belief, however you dress, etc. The fact that the racism which does exist is so virulent comes in part from the fact that it is a minority view.
(2) Truly awesome natural beauty, also very diverse (what's left of it anyways)
(3) Pioneering in LGBTO and abortion rights while much of the world remains a frightening place indeed in these respects.
(4) A away of looking at life in the large and as full of possibility which has brought many bad things but also Jazz, Rock'n'Roll, amazing cinema, etc.