Dublin, a lot of US companies have European headquarters in Dublin. The salary is higher than other EU cities. The cost is higher but if you are in your 20s without kids you can save a lot more than what would save in other cheaper cities with lower salaries. London is big, there are A LOT of things in London. Yes there are more sleazy bankers in London than other places, but London is big, there are lot of things there, don't simplify things that much. It's NOT like 100% of people in Switzerland are only making watches and swiss army knives.

Well there's not a great deal going on in somewhere like the middle of the Forest of Dean as far as software engineering challenges go - you do tend to have to go where businesses are solving problems.. even in a more remote culture the base for companies will be near big cities because big cities are near transport links.

I can only speak for London, but:

* Salary

* Way more opportunities

* Big city life, especially attractive to me, since I grew up in a rural, isolated farming town

It's the same story as the last 200 years of industrialisation and urbanisation.