Edinburgh, Scotland! (Think I'm the first one to post here?!)
We certainly don't have the scale of San Francisco but outside of London it is the biggest tech hub in the UK, I believe. In our office building we have 2 Unicorns- Skyscanner (who I work for) and Fanduel. Just down the road is Codebase, the largest tech incubator in the UK.
I live here just because that's the way life worked out to now. I studied here and got a great marketing role at Heineken after graduation (they were based in Edinburgh at the time, Edinburgh has a tradition as one of the great brewing cities of the world). When I wanted to move away from the world of FMCG into tech, Skyscanner were on my doorstep and I was lucky enough to get a role. There has really been no reason to move away yet, who knows what the future might hold but it's a great place to be professionally and personally right now.