I would probably say Ubuntu, just from the abundance of support that exists for it. You will lose out on a few things, like some cloud services not making official Linux clients, but IMO if you do most everything in a browser, Firefox is fully functional from the moment you boot the installer, and the default app repo includes a bunch of familiar faces like Spotify and VLC.
Personally, I do almost all my "Office"-type work in Google Docs, but the browser versions of Office 365 do work just fine, and Linux has gobs of email / calendar / contacts applications you can try until you find one you like.
Google Chrome is *not* in Ubuntu's default application repository, so I often tell people who ask that if they can figure out how to install Chrome on their own, they can probably operate Ubuntu just fine as an end user.
There is no Microsoft Office for Linux, but people have gotten most of recent versions of Office to run on WINE. It's cool if you don't care about Access or Outlook. And no one should use Outlook for anything anyway because it's awful. You could also get away with running the Android version of Office, which is functionally about the same as the web version.
As I said, I switched to Google Docs and Sheets. I hardly ever make or use spreadsheets, but people who expect to be heavy Excel users are also people who will never stop bitching that no other spreadsheet product is as good as Excel.
I personally don't like Ubuntu at all, its reliance on snaps makes my skin crawl, but for a beginner there really is no better option, as all the tutorials are written with it in mind first. You might try Mint, I haven't used it in any capacity since 2015, but as I understand it it's basically Ubuntu with a more Windows-like DE configuration by default without trying to be a flat-out clone like Zorin was, plus I'm told they don't usually make the same awful decisions that Canonical does. When you know more of what you're doing, Debian has similar application compatibility, it just immerses you more in the deep-end if you choose and doesn't treat you like a total idiot.
Bear in mind LTS distros (Ubuntu, Debian stable) typically use older kernels and thus shouldn't be used for bleeding-edge hardware, I'd say no newer than about two years. I'm currently suffering with a rolling distro on my main PC because I had the amazing idea of using a GPU that'd just been introduced 6 months ago and wasn't similar enough to anything else that something could be easily adapted.
I've not run into anything LibreOffice can't do with enough prodding, but it sometimes does get interesting ideas about formatting in Microsoft-format documents. Honestly these days it's no worse than just opening those same files in an older version of MSOffice.
I actually have a very long and deeply held prejudice against ANYTHING based on Debian because some waste of oxygen from the FSF was shitty to me on IRC in about 1995, but truly, Ubuntu doesn't think commercial software is the devil, comes with the hooks to get almost everything running with next to no effort and it's far and away the easiest thing for which to find help.
Suse was my go-to for a desktop Linux for a long time, but it just keeps getting weirder and weirder and these days everything I actually set up myself is plain old Centos.
I don't pay attention to FOSS evangelists so I don't let any of that bother me. Frankly IMO most folks from the FSF are nutjobs not worthy of your respect or even acknowledgement. I just use what I like, open-source or proprietary. I have a healthy respect for what open-source software stands for, but their messaging is almost always off-base. I don't really care about systemd anymore so I'm done really trying to avoid it except on my desktop and laptop where I'm not running services beyond dbus, pulseaudio, and maybe cups.
Probably a weird choice, but all my servers run Debian. My VPS hosting my website and IRC bouncer, my VM server runs Proxmox which is based on Debian, and my three home VMs (NAS, game servers, and misc network services respectively) all run Debian.
Ubuntu has been my preferred distro for a long time now and highly recommend it. It just works and there's plenty of decent documentation out there for most things you'll end up searching for.
I have a few instances of the latest Ubuntu desktop for GUI-related tasks. I run all of them as VM instances under ESXi and connect to them using Chrome Remote Desktop from my various desktops/laptops.
I use the Ubuntu server version for headless tasks (like this website) and a few other services in my home lab for games, Plex, management tools, etc.
If Red Hat derivatives were off the table, I'd probably take up Slackware, which is philosophically closer to a standard Unix than most anything else. I almost always use Ubuntu if I'm teaching. It's just the path of least resistance.