Similar questions to this are asked periodically, but many of these answers are outdated.
I need to build a cross-platform desktop application in Java with a GUI of comp
I can also offer you a new LaF to look into - WebLaF. I'am currently working on it to bring a lot of UI features and make work with Swing much easier for anyone by just using WebLaF library basic features.
A few examples showing how some of WebLaF components look like:
Some of main goals i am targeting:
WebLaF library also suggests a few other advantages and unique features:
You can try the demo-app to see if it is modern and simple enough :)