If you are starting fresh, the way to go is to install Ubuntu-Gnome. Ubuntu and Ubuntu-Gnome will be merging anyway. Get that here.
If you are like me – using my ubuntu machine daily and super impatient – you can just install gnome and switch to it from the login screen.
Add PPA’s
sudo add-apt-repository ppa:gnome3-team/gnome3-staging
sudo add-apt-repository ppa:gnome3-team/gnome3
Update
sudo apt update
Go for gnome
sudo apt install gnome gnome-shell
You will be prompted at this point to choose between GDM and LightDM. I chose GDM at first, which I read was fine if Gnome was going to be used solely (sharks don’t look back!). I understood that LightDM is the option to choose if you are going to flip between the two. GDM caused me some graphic driver issues that left me unable to boot. I ended up in recovery and ran the above again, this time choosing LightDM. All good after that.
To get the better looking gnome login screen, run:
sudo update-alternatives --config gdm3.css