I want to learn more about file systems from the practical point of view so I know what to expect, how to approach them and what experience positive or negative you had / have.
I found this wikipedia's comparison but I want your hands-on views.
For now my mental list is
NTFS - for some reason TVs on USB love these and also Windows + Linux can read and write this
Ext4 - solid fs with journaling but Linux specific
Btrfs - some modern fs with snapshot capability, Linux specific
xfs - servers really like these as they are performant, Linux specific
FAT32 - limited but recognizable everywhere
exFAT - like FAT32 but less recognizable and less limited
ext4 on all hard disks, but my installs are all several years old at this point, and I might choose differently if I were starting over from scratch. The boot partition on the ancient laptop might actually be ext2; I don't remember and it's certainly old enough that that might still have been preferred Gentoo procedure when I first set it up. Removable media might be ext3, ext4, or vfat, depending on compatibility needs and how long ago I formatted it. If I buy an SD card or USB stick that turns out to be preformatted in exFAT, I reformat it before use to ensure everything can read it.
They're all solidly reliable filesystems (well, except for the vfat), but perhaps not the most featureful.
Yeah same here, everything is ext4 'cause it's always worked and has never given me any troubles. But next time I have to reinstall I am tempted to give Btrfs a go.