Canonical recently released Ubuntu 19.10 and it fully supported on the Raspberry Pi 4!
In this video, I show you how to install UBUNTU 19.10 Desktop on the Raspberry Pi 4 from start to finish and I even go over how to overclock the Pi4 up to 2ghz just to get a little extra performance out of your system. You can also install Lubuntu, Kubuntu, and Xubuntu on the raspberry pi 4 if you prefer a different Linux distro.
Download Ubuntu Raspberry Pi4: https://ubuntu.com/download/iot/raspberry-pi
Download etcher: https://www.balena.io/etcher/
Download Notepad ++: https://notepad-plus-plus.org/downloads/
Overclock Text file HERE