I highly recommend Go. It is the most fun I've had learning a new language since Java.
(I don't enjoy Java programming nearly as much these days as I think the language has mostly languished and I'm not too fond of the FactoryOfFactoryFactories culture that has grown around it).
Even if you don't end up using Go a lot, it will make you question a lot of the complexity that is taken for granted in other languages you use and probably also make your code better in other languages (not in the sense that you will do things exactly the way you do them in Go, that would be foolish to attempt, but in the way you may begin to approach things with a fresh set of eyes in terms of how much flexibility you can maintain while also starting from a small set of simple concepts).
(I don't enjoy Java programming nearly as much these days as I think the language has mostly languished and I'm not too fond of the FactoryOfFactoryFactories culture that has grown around it).
Even if you don't end up using Go a lot, it will make you question a lot of the complexity that is taken for granted in other languages you use and probably also make your code better in other languages (not in the sense that you will do things exactly the way you do them in Go, that would be foolish to attempt, but in the way you may begin to approach things with a fresh set of eyes in terms of how much flexibility you can maintain while also starting from a small set of simple concepts).