Ubuntu is one of the best open source operating system in the world, It’s more stable, more User friendly and comes with almost every sort of software pre installed in it.
You can’t infected with virus when using Ubuntu so that’s one less thing to worry about as well.
When it comes to selecting wallpapers for Ubuntu, many just google wallpapers for them and simply put them as wallpapers although normally it’s a common practice amongst the average user but what they don’t know is that they should try to use HD Ubuntu Wallpapers only because those HD wallapers specifically made for Ubuntu rather then other Operating system.
People who uses Windows “Bliss” wallpapers are really stupid kind of people because if you really want your OS to feel like Windows so just get out there and buy one rather then making a good OS look bad.
There are tons of sites from where you can get Ubuntu, Linux, Fedora, Redhat, Zorin’s and others wallpapers free, just Google them and you’ll find sites providing HD Wallpaper for Ubuntu easily.
Websites I Reckon
They have a huge variety of wallpapers you can choose from, they provide 100% free full HD wallpapers for Ubuntu with no strings attached