What do you suggest? I’ll try it in a VM or live usb.
Regardless of which distro you choose, your "desktop experience" will be mostly based on what desktop environment you pick, and you are free to switch between them regardless of distro. Ubuntu for example provides various installers that come with different DEs installed by default (they call them "flavours": https://ubuntu.com/desktop/flavors), but you can also just switch them after installation. I say "mostly" because some distros will also customise the DE a bit, so you might find some differences.
"Nicest desktop experience" is also too generic to really give a proper suggestion. There are DEs which aim to be modern and slick (e.g. GNOME, KDE Plasma, Cinnamon), lightweight (LXQt), or somewhere in between (Xfce). For power users there's a multitude of tiling window managers (where you control windows with a keyboard). Popular choices there are i3/sway or, lately, Niri. All of these are just examples, there are plenty more DEs / WMs to pick from.
Overall my suggestion would be to start with something straightforward (Mint would probably be my first choice here), try all the most popular DEs and pick the one you like, then eventually (months or years later) switch to a more advanced distro once you know more what your goals are and how you want to use the system. For example I'm in the middle of migrating to NixOS because I want a fully declarative system which gives the freedom to experiment without breaking your system because you can switch between different temporary environments or just rollback to previous generations. But I definitely wouldn't have been ready for that at the outset as it's way more complex than a more traditional distro.
I ended up booting Mint with Cinnamon. I like it. It's pretty intuitive coming from macos/windows, and I'm in the terminal half the time anyway. Installing the nvidia driver was easy, then steam does a good job installing whatever compatibility layers it needs. I'll do CUDA next and try it for a month or so.
One warning: keep in mind that if your desktop PC motherboard has a mediatek wifi+bluetooth chip, that chip will probably not work on any version Linux (AFAIK). I don't use wifi on my desktop but I do use bluetooth game controllers. You can replace the chip (which is what I did, with https://www.amazon.com/dp/B08MJLPZPL), get a bluetooth dongle (my friend recommends https://www.amazon.com/Bluetooth-Wireless-External-Receiver-...), or get a PCIe one.
Bon appetit!
I heard Kubuntu is not a great distro for KDE, but I can't comment on that personally.
If you care a little more about your privacy and is willing to sacrifice some commodity, go for Fedora. It's community run and fairly robust. You may have issues with media codecs, nvidia drivers and few other wrinkles though. The "workstation" flavor is the most mature, but you may want to give the KDE version a try.
If you want an adventure, try everything else people are recommending here :)
If you want something that "just works," Linux Mint[1] is a great starting point. That gets you into Linux without any headache. Then, later when bored, you can branch out into the thousands[2] of Linux distributions that fill every possible niche
Fedora is so significantly better.
I wouldn't confuse popularity for good. Ubuntu gave away free CDs in the 2000s and are living off old marketing.
Debian family is so bad. You will be in the terminal constantly just trying to get stuff to work. Stick to a well maintained, up to date, consumer distro, Fedora.
(reminder that Fedora is Not Arch)