Which filesystems support symbolic links? I'm copying a big archive of files from a Linux host to an external USB hard drive, that will then plug into a macOS host.  The copy should preserve the archive's many symbolic links (ln -s).  What filesystem should I format the external disk as?


Not exFAT, because that doesn't support symlinks.
ext4 can be mounted only read-only, via e.g. ext4fuse.
Something else, that can mount read-write?  (Must also be writable by the original Linux host, Ubuntu 16.04.)
HFS+ (Mac OS Extended Journaled)

Why? 


Supports Symlinks
Read/write on macOS natively
Easy installation for read/write on Linux


See this for Linux installation tutorial.