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Do you actually want to switch distros? Or just interested in what's out there?
If Fedora 39 didn't satisfy you, then what exactly is bothering you?
What is it that you seek from your distro? Being out of the way? Freedom? Polish? Blank slate? Security? Privacy? Ease-of-use? Up-to-date? Big repos? etc
I have distro-hopped before so i don't mind switching
I need a distro which is package-agnostic since i use a lot of old ooen source academic software and they alternate between being only supported on RHEL or Ubuntu
Fedora 39 is great except when i need to build the above mentioned software from source and i spend 2 hrs failing to match the dependencies from Ubuntu
Also want to improvey laptop's battery life, but i think i can't get it much better than in Fedora
I need a distro which is package-agnostic since i use a lot of old ooen source academic software and they alternate between being only supported on RHEL or Ubuntu
Perhaps you should look into container solutions like e.g. Distrobox. You can basically install/run any package; just ensure usage of the correct container environment.
Fedora 39 is great except when i need to build the above mentioned software from source and i spend 2 hrs failing to match the dependencies from Ubuntu
If you're otherwise content with Fedora, then perhaps consider installing the aforementioned Distrobox; which happens to be found within Fedora's repos and thus one sudo dnf install distrobox away from being installed on your machine.
Also want to improvey laptop’s battery life, but i think i can’t get it much better than in Fedora
I'd argue that Fedora is not best for battery life, though. Minimalist distros tend to be a lot better at this. Installing auto-cpufreq in Fedora Silverblue on my AMD-powered laptop did come with significant improvements, so perhaps you could prolong your battery life by utilizing it or similar programs; think of TLP, thermald etc to name a few.
I looked into distrobox and checks all the boxes but there is the issue of my lack of storage space(currently only 130 GB left out of 240)
It can definitely fill up space if you're not careful. Just ensure that only the minimal amount of containers and their respective images are on the system.
I would assume one container each for Ubuntu and Arch should suffice for most people. Sure; this will likely take up to 10 GB of extra storage in total (eventually), but foregoing this solution means that you'd likely have to settle for Arch (because of the AUR) or something like Gentoo (because no other distro does compiling and building from source like Gentoo does).
If you feel particularly adventurous, you could also consider Nix and/or NixOS; though you'd have to ensure that said packages are available as a nixpkg. Nix can also be installed on Fedora; consider Determinate Systems' installer for that*.