I would choose Go. It comes with an excellent built-in package net/http (https://godoc.org/net/http) that quickly allows you to setup a web service. An Go's mechanic (?) of implicit satisfaction of interfaces allows you to do some really cool things. One of the gripes about Go seems to be error handling, and your code ends up with a whole bunch of 'if err != nil { stuff }'.

Matt Silverlock (http://elithrar.github.io/article/http-handler-error-handlin...) talks a bit about how you can use some of Go's strengths to create a web services without any frameworks or packages that aren't built-in. Go and net/http is very powerful and allows you to do very much without needing any external packages.

If it was up to me, I would write the service in Go and run it in a container somewhere. But the container is not required :)

Go has been a bit lacking in debugging options previously as you said, but lately cool projects like godebug https://github.com/mailgun/godebug and Delve https://github.com/derekparker/delve have been released, making it possible to debug programs better.