There are so many distros that it really depends on your use-case and it's hard to make a generic suggestion. Ubuntu is a common recommendation for first timers, mainly because as the most popular distro you'll easily be able to Google when you need help with something, and it also uses the most popular package format (.deb). There's also Linux Mint which is basically Ubuntu but with some of the latter's more questionable choices removed (e.g. snaps) and minus the big corp owner. By using one of these you'll also be learning skills relevant to Debian (which Ubuntu is derived from) which is a solid choice for servers.

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.