Ext4 is probably going to be the fastest. When it comes to reliability, old is good. If you don’t need any of the features Btrfs and ZFS, you’ll reap higher performance using Ext4. Otherwise ZFS is more feature-complete compared to Btrfs, however it’s generally not available as root fs option in OS installers. Ubuntu used to have it as an experimental option but I think that’s gone now. If you know what you’re doing you can use it as a root fs. Personally I’m using Ext4 on LVMRAID on a 2-way NVMe mirror. I might be switching to ZFS on root when I get to rebuild this machine. All my storage is using ZFS.