My wife’s laptop absolutely has to work. For some mad reason I decided on Arch for it. Actually a rolling distro is not so mad. You get the latest stuff and in general issues are fixed as quickly as a LTS jobbie or you get a work around in the forums or you dig out the source and a compiler. It’s no accident that the Arch wiki is an oft cited resource. Its not for everyone!
I’ve been looking at a similar thing for my company and Kubuntu so far is my choice and I’ve already ditched the LTS bit. I need to run AV and the usual corporate bollocks to pass silly tick box exercises, so my options are rather limited.
There is no perfect one size fits all distro, that’s what we have rather a lot of them to choose from - they rise and fall according to natural selection and not artifice. Imagine if all computers were sold with a free/libre OS or none at all and Windows or Apples were a paid for add on. Monolithic OSs are completely deluded about being able to cater for all, without some dreadful contortions.
Anyway, back to the job in hand! If you want a LTS then you must accept older software or you use an LTS as a base and add newer stuff yourself. Most Linux distros allow you to run your own add-ons formally or informally. Gentoo has a rather nifty user patching mechanism for distro ebuilds and you can have your own ebuilds take over entirely. RPM and pkg distros can handle user packages and Ubuntu has PPAs too. I could go on. Also you can go off piste and put stuff into /opt and/or /usr/local!
Please reconsider your use of the term “unstable”. I suggest you write down a list of your requirements and score them according to importance. Then grab a list of OSs and distros - all of them, don’t preclude Windows and Apples: they have their uses. Then score the OSs/distros against your requirements. The scoring might be in the form of a matrix (table). I suggest keeping it simple with a score of -1 to 1 for each item (-1=dislike, 0=neutral/whatevs, +1=like)
Do a pilot project and see how that goes. Take your time. If it is for personal use then run your tests in a VM. Most modern hardware can easily run a VM or two. Virtualbox or VMware Worskstation or KVM (libvirt is a good effort)
The choice is yours. Note that word “choice” - its very important.