I know this sounds random but I am trying to get a collection of brightly colored pictures for my desktop at work.If you know of any or any sites that provide excellent wallpapers and background, please share!
Maybe some of these will be for you -> https://wallpaperscraft.com/tag/bright/1920x1080
Another good site to check is DeviantART.
Here's an excellent collection from which I am using some from: http://wallpapercave.com/bright-wallpaper
I guess it depends on taste. When looking online use words like HD, High Quality, Vivid, and Lush. You will get a wider variety of more stunning pictures. This is my background and I found it on a simple Google search: