An LTS Ubuntu release should be fine, though I'd hold off on using it in production until a year or so after release (to give Canonical time to shake out bugs).

A non-LTS Ubuntu release should be avoided, since they tend to be less stable.

If you're using something in the Debian family, Debian itself is probably the much better choice unless you're looking to use Canonical's enterprise products.

I think it can be used in production but it's more work. Red hat and CentOS can be hardened following STIG security profile on first boot from fresh install which includes SElinux checks, firewall and service configurations, etc. I'm sure there's more to it, but reading documentation on these alone is enough to overwhelm me.

In my experience:

- Ubuntu is not stable

- it is not hardened out of the box

- it can contain dangerous configuration out of the box

- it calls home

- it will tempt you to install dev packages or other packages unfit for production (because devs dev on ubuntu and they require the dev packages)

But please, don't mind me. Other people are better at explaining this. I'm biassed.