The ecosystem and tooling are great, probably the best I've worked with. But the main reason I reach for Go is that it's got tiny mental overhead. There's a handful of language features so it becomes obvious what to use, so you can focus on the actual goal of the project.

There are some warts of course. Heavy IO code can be riddled with err checks (actually, why I find it a bit awkward for servers). Similarly the stdlib is quite verbose when doing file system manipulation, I may try https://github.com/chigopher/pathlib because Python's pathlib is by far my favourite interface.