For example, I'm using Debian, and I think we could learn a thing or two from Mint about how to make it "friendlier" for new users. I often see Mint recommended to new users, but rarely Debian, which has a goal to be "the universal operating system".
I also think we could learn website design from.. looks at notes ..everyone else.
OpenSuSe - snapper for taking btrfs snapshots and rolling back. It’s basically a bulletproof way to do updates and recovery. Get a bad update or change a config in correctly you can roll back. Updates it automagically does this for you