I also think that they are trying to position .NET Core as a viable competitor to Java, for which they need decent cross-platform tooling.
I have to admit, since I switched from Atom to VSCode, I'm also re-evaluating other Microsoft products. I even bought a copy of Win10 (but it wasn't as good as I hoped, haha).
Also, I worked with a few DevOps people who really hated AWS usability and some of them said Azure should be much better.
The transition of Classic to ARM (Azure Resource Manager) made me drop Azure for AWS. Now ARM is more or less stable so there's no issues, but damn when they started it was complicated.
But in terms of UI...
GCE > AWS > Azure.
As for go, GoSublime is pretty good, I'm hesitant to go to a javascript based editor when Sublime offers such good go support.