I've lived and worked in the startup scene in London for a few years, and I've lived in Berlin for three months too. Language-wise: You can get by with English

I've lived and worked in the startup scene in London for a few years, and I've lived in Berlin for three months too. Language-wise: You can get by with English fine in Berlin (not true in the rest of Germany though), English is pretty common in the startup world. Even generally English is pretty widely understood by younger (i.e <35) Berliners although fewer of them speak it fluently. London has by far the biggest ecosystem, Berlin has a decent one although much more early stage. Barcelona is tiny, see this infographic: http://seedtable.com/blog/images/startuphubs2012.png http://seedtable.com/blog/images/startuphubs2012.png Rent is much more expensive in London than in Berlin, but on the other hand salaries are also higher in London. As a ruby consultant or working for a growing funded startup you won't struggle financially. Sharing a nice flat with 1-2 other people you can expect to pay £600-£1000/month, it should be comfortably affordable even on a junior ruby dev salary (~30k/year). With London you'd have a much wider range of startups to choose from, but with Berlin you'd have a much more laid-back culture and lifestyle. Based on your criteria I wouldn't choose Barcelona based on the lack of ecosystem and very limited number of companies who deal with serious scaling.