I've been using Debian for years now. Decades in fact! If Stable is not up to date enough you can move to Testing, which I did for a while without any problems, but for now am just sticking with Stable. Its always worked perfectly. Debian is where people end up.
I use Fluxbox myself, as WM, which I find perfect, and Lightdm as DM. Its fast, keeps out of the way, handles workspaces very well, i have lots of keyboard shortcuts which makes it very convenient. It has a really neat feature, you can combine different apps into tabs in the same window. So for instance, you are writing something and need to refer to a web site and a spreadsheet as you write. You have all three apps open in tabs in the same window and can just click back and forwards between them.
I have put in MATE on Debian for someone else, and that has worked out very well. MATE is also very simple and keeps out of the way, and the team have the rare ability to refrain from fixing what works. Its about like Gnome 2 used to be, before they went crazy and ruined it.
Debian is Systemd now, which I don't much like. If you want Debian without Systemd, then probably MX Linux. I might go for this if changing distros, but am not bothered enough to move from Debian for it. Or there is Devuan.
Mint with MATE for someone I put it in for was also fine. It depends what you want, Mint strikes me as full-on consumer grade. Whereas if you install plain Debian, Fluxbox with Lightdm, tweak the right click menu, startup and keyboard shortcuts to suit you, you have something which will probably suit you better and keep out of the way, but it would not be fair to install that for a naive user.
I have tried tiling WMs, but they are not for me. i3 is said to be the best.
So I think this is a vote for Debian with Fluxbox. Or, if you want to keep away from Systemd, MX Linux.
One reason for going with Debian is that its going to be around for ever. Not sure about some of the less used distros, and that is a real factor for me.
And if you decide you want a full-fat consumer experience, Mint. There is not going to be a huge difference between Mint with MATE and Debian with MATE. You could also put Fluxbox on Mint. I think Mint, like Debian, will be around.
I have tried Arch in a VM, and didn't care for it, but it has a great user community and excellent documentation. Matter of taste, really.
I use Foxclone for backups by the way. Really recommended.
Peter