@matrix NFS if you're just doing linux-linux (or any unix) - it's the fastest but least secure (literally depends on your network being secure, unless you want to mess with kerberos). Samba is a bit more secure and a bit more cross-compatible but might have issues. WebDAV and FTP((E)S) are not really meant for "mounting" but can work, but with other protocols those are usually used for remote access. SFTP i.e. file transfer over SSH, is THE slowest, compatibility on other devices can be worse than FTP((E)S). Lastly, if you're just mounting a folder on one device ever and never going to share it - iSCSI is probably the way to go.

Lastly - word of advice - don't share same directory using multiple protocols at same time (especially if one of those protocols is NFS), it's doable but not very stable, and different servers will get really confused about ACLs.