I find swift the worst choice for a start-up right now. Why would you use a language that's only half baked? Don't you have more important things to do than porting the standard library to linux? Not to mention the lack of concurrency. Go can be a grat choice for all sort of systems too and in many cases better than any of the languages you listed. It's about using the right tool for the job and I think your comments about Go are plain ignorant.