The main advantage over arch for a user like you is that, whenever you write something to a file in /etc or or otherwise install packages and change configuration because you finally figured out how to solve e.g. suspend not working, you will be able to put that change in a git repository.
Next time you install a computer, instead of having to relearn all these little things from the arch wiki and spend months getting everything perfect, you’ll just reinstall your NixOS config and all those little things will just come preconfigured. You can also read your code and leave comments for yourself to understand why and what you did.
I doubt any arch user will have been using the distro for three years without ever making a change they have forgotten about by now; just imagine how hard it would be to get back your current system if your SSD broke. Speaking from experience, you’ll never get it back 100% - NixOS, when used correctly, makes 100% easy.
The downside is that you’ll need to learn a programming language to achieve this, and you’ll have to work around a lot of little paper cuts where NixOS’ unusual nature makes things a bit harder than on traditional distros.
So, personally, I think the answer to “should I use NixOS” - specifically for these personal computer use cases - depends on how much effort you think you’re willing to put into learning (think at least a few months to get comfortable, a year to get confident), how much running into tedious little problems all the time annoys you (NixOS has more of that than other distros, you’ll need to rollup your sleeves occasionally), and how annoying you find it that you can’t easily get a computer in working order again. If you’ve not seen much of the development side of software the learning curve will be even more steep.
Once you understand it, however, NixOS is incredible. No other distro comes close to what NixOS offers to a power user (except the guix semi-fork, I guess). Many who get to that point never want to switch away again: Why did you come to NixOS (if you are using it)?
Keep in mind that if you’ve only ever tried one distro, you won’t really know what you’re missing out on 
We humans have a tendency to stick with the first thing we learn/try out, it takes effort to actually go beyond that and experiment.
Arch “just works” because you’ve spent the time learning and configuring to make it “just work”, and all the little things that take some effort are already second nature to you. This does make arch more attractive right now, because you don’t need to learn anything new… But maybe you do want to broaden your horizons 