There are a lot of Ubuntu boxen in production out there. It is basically the default for Linux VMs in Azure, the UX sort of pushes you that way unless you have a particular preference otherwise. I do have a preference, for Debian which I've used at home for many years, but in DayJob Unbuntu is close enough and seems to make others more comfortable (in part due to the impression some have that it is better supported in Azure). I'm surprised MS aren't nagging Ubuntu to pull their finger out for this reason (maybe that are, behind the scenes, but if so it isn't working).