This has been in the back of my mind lately as I think about bouncing between OSes. Typically various Linux distros seem to be able to recognize just about any filesystem, but the same definitely can’t be said of Windows, and I suspect MacOS as well.
I’m mainly thinking about whatever would allow you to plug a drive into a computer or smartphone (more of an edge case here tbh, but it’d be a nice bonus) and it be recognized without issue.
For native support I guess the best non-journaling filesystem would be exfat if you’re planning on storing files that are +4gb in size which will work on any up to date operating systems (not 100% sure about iOS) but you might run into trouble with older operating systems. As for journaling no clue but I wager NTFS but that would leave out mobile operating systems and maybe macos but not 100% on this one. I know that it works with Linux and windows since that’s the one I used to use but I since moved away to ext4 after fully committing to the Linux style.
Edit: looks like iOS supports exfat. Macos only supports reading NTFS but not writing so whomp whomp