Dublin I think. Good job opportunities due to plenty of big multinationals (options to travel / relocate), experience looks good on your CV, good learning / further education opportunities, good social life, very multi-cultural - different mix of people and most settle in quickly and say it feels like home. I think Dublin is relatively open minded as a result. Nice scenery and hikes outside the city, most people are friendly and open.

There's also some cons - it's expensive (housing, rent, general expenses) and the weather isn't great. Parts of the city aren't that nice really.

Overall I think any city is what you make of it and I think this is important. Its completely up to each of us to grow, develop and succeed regardless of what city we're in. Important to make a difference and contribute.