I guess for us these would cover it all
1. Opportunities.
2. Weather
3. Lifestyle
4. Peace of Mind
5. No traffic issues
6. No corruption, the taxes are used at the right place rather than going in the officials pockets.
7. A better future for our kids (whenever they are born )

I guess it must be the same with most of the people. I mean, why would anyone move from their comfort zone and go on a crazy shifting spree, discarding things that you love and could not carry etc etc etc.. Afterall moving countries isn't cheap.