Oddly I’ve been missing Unity since the moment they removed it from Ubuntu…
Gnome it’s slow, takes a lot of resources and not really stable at least from my experience…
Installing Unity
Install by using (315mb)
sudo apt install ubuntu-unity-desktop
This comman will install Unity last version and all suggestions, 2.2gb
sudo apt install ubuntu-unity-desktop --install-suggests
During installation, you have to choose the display manager. Choose lightdm.
How to remove Gnome?
I still do not hate gnome that much but sooner or later… will disappear…
sudo apt remove gnome-shell