I have also left Python for projects where I can chose the tools, but I have not stuck with Go. I went to Racket which has much like Python a "Batteries included" feeling, it is a very easy language with a lot of power and a really good JIT compiler. For me, it is perfect for exploration and algorithm design. For example, I could develop an algorithm in Racket and easily port it to C++11 which was what the client / employer ultimately wanted - still having a much quicker total development time.

For things that are performance-critical or require high reliability, I have successfully used Rust, even if I am still much slower writing it. One thing I like is that the resulting code is not more verbose. Which also means that it is easy to read even after months of not touching it.