This is just my not-at-all-in-depth summary based on playing around with a few in VMs, but as a non-power-user:
Fedora Silverblue
Pros: Good support/documentation
Cons: barebones Gnome/required layering quite a few packages if you want any kind of customization before I could get my system up and running
OpenSUSE Aeon (MicroOS)
Pros: good number of built-in tools (e.g. Tweaks, distrobox)
Cons: documentation is sorely lacking
Vanilla OS
Pros: great ease of use/installation, container-centric
Cons: still very much a work in progress/small dev team
It's also worth mentioning Universal Blue which is based on Fedora Silverblue but has multiple variants with additional doftware. It seems like you can rebase an existing Silverblue system to it and also switch back without reinstallation.
The cons for Silverblue aren't really fair, you can customize the GNOME desktop at will installing Extension Manager from Flathub, and a lot of CLI tools you'd layer you can get working through toolbx/distrobox, and barebones GNOME is literally the same as stock Fedora.
The customizing one most definitely isn't. As straight out of the box you can go to extensions.gnome.org and add all the extensions you want.
Now the big problem is the codecs, those have to be layered for proper vaapi/vdpau support. Then I had to layer a different kernel (Surface Pro), and different power management (tlp, since power profiles daemon gives terrible battery life).
While it's a con that I have to do this, it's also a pro that I'm able to do this where many of the other immutable distros don't allow this.
If you stick to Flatpak apps you don't even need the codecs on your base system (I've been using it myself this way for a while now). For power management, I personally prefer to layer powertop, which doesn't break power-profiles-daemon and works basically just as well as tlp, but layering tlp is perfectly fine too.
The custom kernel though, that's more complicated (and an understandable limitation to immutability), I'd recommend you look into Universal Blue in your case, as it might be a better solution.
Hmm.. I thought at the very least you needed to layer intel-media-driver for VA-API support for Intel.
Yeah, powertop is essential and should come in the default image. How else are you going to see exactly how much power your machine is using at any time? I wish PPD+Powertop --auto-tune worked for me, but the powersave scheduler it uses lets my Alder-Lake CPU run wild and gives me a good 2-3 less hours of battery life.
I plan on sometime investigating how to make my own image using Universal Blue, because really all I need is Silverblue+Surface Kernel+TLP+Hardware Accelerated Video. But too busy right now.
Yeah, I didn't really explain myself very well, in retrospect
Like Fedora Workstation, there were quite a few packages that I needed to add after the initial installation - Gnome Tweaks, RPMFusion, Flathub, third party codecs, etc.
Silverblue being immutable made this process more of headache than I felt it should have been.
Flathub comes out of the box since F38 and with it you basically don't need RPMFusion and third party codecs. Even NVIDIA you can get out of the box without the need for the entirety of RPMFusion (which is what I personally do).