From my experience, most FOSS software is very user friendly user-centric / user-focused, while proprietary stuff is shit. What is the most notable exception to this rule that comes to your mind?
Edit: With user friendliness, I don’t mean UI design, but things like how the software is handling user privacy, whether it sees its users as users or as money-making cattle, how it handles user feedback, compatibility with other software the user uses (vs. vendor lock-in), configurability, and similar issues.
Edit2: I was made aware that user friendliness is a defined term: https://en.wikipedia.org/w/index.php?title=Userfriendliness
As someone else pointed out, the premise of this question is extremely faulty. Being user-friendly is one of the main advantages of proprietary software because they have teams of researchers and designers making sure that things are as frictionless as possible for the user. This isn’t to say they don’t use dark-patterns or engage in anti-consumer practices, but I’m certain that if you did a random sampling of F-Droid and the Play Store, you would find a lot more polished and user-friendly software on the Play Store than the FOSS apps on F-Droid