If you are looking for a nice looking XFCE icon theme, consider and try Qogir icon theme. This icon theme is developed by vinceliuice so feel free to explore his work.
Qogir icon-theme is developed for light and dark themes, for any Linux operating system, but there are also versions that are specially designed (color-matched) for Ubuntu and Manjaro Linux. There are customizations for dark and light themes in all versions and it’s great.
I specifically emphasized “XFCE icon theme” in the title because I use MXLinux which, with a few modifications, looks great with this icon theme. You are free to try this theme wherever it suits you. Here’s how:
How to install Qogir icon theme
Download theme from here vinceliuice/Qogir-icon-theme.
To download the package click on the button “Code” and from the drop-down menu select option Download ZIP.
Unpack the theme package. You do this when you right-click on the package and select the Extract here option.
Navigate to the folder that was unzipped. Open Terminal in that location (inside the folder that was extracted). You can do this easily by going into the folder and right-clicking, then selecting the Open Terminal here option.
Type in Terminal:
Press Enter and wait for the installation to complete.
Now to to Appearance (if you are on XFCE) and select you new icon theme:
Here’s what the Qogir theme icons look like: