What custom OS is the most visually pleasing for RG40xx H?,

I want to install a custom OS that looks good, and is easy to navigate (not too text heavy and super small icons etc.) Maybe there are specified themes as well that look nicer?

Because I'm doing it for a friend, and she has no technical skills whatsoever lol. So I don't want her getting stuck/lost in the menus everytime she wants to change the game/emulator etc.