I've been using Linux for a long time, which might sound like I'm comfortable with all its rough edges, but it's honestly the opposite. Early on it was a new toy and I would accept issues as part of messing around with it. The past 10~15 years on the other hand, I've needed to get serious work done on it, and also use it for PC gaming, so I've gone the other way and focused on getting the most no-nonsense easy setup where I don't have to be tinkering with things all the time.

Based on that, I'd say: go for a popular distro with KDE. I'm sure there are other very polished options out there, but my recommendation is Kubuntu, even though it's not the one I use today (I use Arch mostly), as it's very simple to set up and well supported.