As for your DPI issues, I've heard many have had better luck with Wayland than Xorg.
Gnome has a feature in Wayland (Ubuntu has a third-party patch for X11) that scales up to an integer ratio then scales the image back down to fit the right size by making the display frame buffer larger. This is what Mac OS does. It’s slower here than on Mac OS, so it’s not very optimized, and it leaves things ever so slightly less sharp.
I pretty much only use Firefox and terminals. So I set ~/.Xresources Xft.dpi to something that looked nice. Presumably a bunch of programs ignore this (otherwise I wouldn't be seeing complaints about HiDPI online).
Plasma is great and it feels lightweight compared to Gnome
Really interestingly I've been using a Windows, a Linux and a MacOS machine for many months, swapping them often. Well, Windows/Linux are on the same Ryzen 2700X with a Geforce 1080Ti, the Mac is a 2018 Mini with 32G RAM and 6 core i5. 4k 32" display in each case.
What surprised me: - Windows UI is WAY the fastest. Linux is the slowest, and with fractional scaling turned off its hardly tolerable
- the font rendering on Windows is perfect, while MacOS is a bit blurry. This is very surprising to me since all the hype around the good scaling of MacOS. Windows hidpi fonts are just perfectly sharp.
- MacOS is absolutely consistent when it comes to rendering and scaling, the others aren't
Personally, I've turned off AA on my PC (and it's a completely useless feature on high resolution displays). What surprises me is as we have been moving into higher resolution displays, the OS makers have been making it HARDER to turn off anti-aliasing of text and this includes newer versions of Qt which have it turned on apparently so programs using Qt now pick up anti-aliasing even if your PC has it turned off.
People go on about how they love their blurry fonts. I don't get it. I like crisp and sharp.
PS. The version of the font, and the font used also makes a difference. A number of them were made during an era when anti-aliasing wasn't as common, so those are hinted to work well without AA, but I have also run into situations where an older version of a font works great with AA off and the newer version of it doesn't because they screwed something up or removed the hinting in the newer version. So if you have a really good font, back it up.
Also, I have 4k, 28" monitors which is just the size where 1x is comically small, and 2x is comically large. I've tried recent Gnome and KDE, and they just can't scale to look right, like what I can do in MacOS or even Windows.
If I couldn't use MacOS for work, I would give Windows 10 a serious consideration. The new WSL and Windows Terminal are very good. I did use WSL 1 for a few years at a previous job, and it was awful.