Linux

Linux Mint Cinnamon. Stable, yet tons of customizations possible and makes the jump from Windows a whole lot easier (I jumped 1.5 years ago and will never look back).

Kubuntu or KDE Neon 100%

Ultimately they both use the KDE Plasma desktop environment, which is the only DE I've ever seen that has a proper modern look by default (others IMO look like either the 2000's or an OS 4 Kidz), as well as being pretty featurful for multi monitor productivity

Arch+KDE Plasma is what I personally am gonna switch to this summer

You can use most desktop environments on most distros.

If a distro has its own GUI and it doesn't exist on other distros, usually that means either it isn't free software or it's not good enough that anyone has bothered to package it for other distros.

I've been preferring KDE lately tbh. Very flexible and familiar. Still don't know what that activity thing is for though lol

Probably any distro that ships KDE Plasma 5 as default - I'm stuck with GNOME for now as I need to use Evolution for work (EWS mail accounts), but if I had the choice I'd probably be on Plasma.

I used the Pop Os default for a long time and just recently switched to i3 Manjaro, it’s been pretty nice once you get past the learning curve of i3

Distro is irrelevant. DE/WM choice is all that matters as far as GUI goes. Also, if you want a GUI that looks or feels like windows then KDE probably has you covered in that you could probably customise it to mimic windows.

I quite like the Desktop Environment in elementaryOS. I think it's called Pantheon Desktop? It's very polished. Or InstantWM from InstantOS is also interesting and has some nice animations and effects.

Personally, I use simple and minimal Openbox

Fedora with Gnome

Fedora. It ships vanilla GNOME which is just a very pleasant experience. Vanilla GNOME is just something else man.

For some reason I find stock GNOME UIs appealing

Currently I am using Cinnamon with Debian and quite like it. Previouly I enjoyed XFCE, espacially on slower laptops. Never really liked GNOME or KDE Plasma though. GNOME has too many animations and feels slow. At the same time its not very customizable. KDE on the other hand feels slow as well and though it is kind of fancy it seems not to be my taste and I did not like the way you customize either. That is not so important to me anymore. So please don't read from this that Cinnamon or XFCE would be great for customization. I would not know it.

It thoroughly depends on how much you're willing to configure

I think right now EWW + hyprland is the new hotness, if you're willing to edit text files and scripts

If not, go KDE if you like windows, gnome if you like mac.

Absolutely love GNOME on Fedora. Workstations + Hotkeys are amazing. I really dig the minimalism and compartmentalisation it offers.

I run tiny core linux for the UI personally

Deepin is great too. Unfortunately it is not fully translated so that you come across Chinese quite often.

Distro? Probably Debian, because it has all the desktop environments. If you want, you can have Plasma, Gnome, Xfce, Cinnamon, and MATE all installed at the same time and switch between them at will. Most distros seem focused on one specific DE, which if I'm not mistaken means switching to another involves reinstalling the whole operating system.

The big downside of Debian is that the software in it tends to be very out of date. You'll get security updates and the occasional bug fix between Debian releases, but that's about all you'll get.

You can get a rolling-release experience by running the “unstable” version, but as the name implies, upgrades will sometimes fail or break something, and you need to know your way around the system in order to recover from that. Not a problem if you want to learn to be a Linux sysadmin anyway, but if you want your system to Just Work™, then unstable Debian is unfortunately not for you. It's a trade-off, as with most things in life.