I thought a lot about this topic too as I am coming around quite a bit with my job. And there are definitively many cool options available.
In the end it all depends on what is important to you, it's a trade off between different factors. If you go for the best kitesurfing all year round and want some warm water, Brazil is hard to beat. But if you can live at two different places and switch from season to season, you have many more options.
My list:
Cape Town, Buenos Aires, Boston (Cape Cod), Cumbuco, Tel Aviv, Cabarete, St. Moritz, Perth, San Francisco, Copenhagen.
If safety is a big topic for you, Cape Town, Cumbuco and Tel Aviv are probably not high on your list anymore...
If you need some cultured civilisation nearby, Cabarete is only in the list if you don't mind that the you need a plane to get to the next "real" city...
If you are not speaking Spanish or Danish, Buenos Aires resp. Copenhagen will not be the easiest place to live in then...
If you like a European lifestyle and many offers in regard to culture, Perth might not be the place for you...
If kitesurfing is much more important to you than to be near a cool city, Boston/Cape Cod falls out of the list...
If you are not able to snowkite and need to watch your budget, St. Moritz is not the place to go...
If you hate cold water, SF sucks. I could go on and on...
But still, those places I just mentioned are pretty high on my list.
For me, the best choice right now would be a split between Cape Town and St. Moritz as these places are almost in the same time zone and are both pretty cool. But yes, there are definitively places with warmer water around as well...