rsync -av --progress /Users/username/Desktop/example_file.tif /Volumes/OpenShare/RSYNC_TEST
source -> destination
The flags are:
v increases verbosity.
a applies archive settings to mirror the source files exactly, including symbolic links and permissions.
E copies extended attributes and resource forks (OS X only).
progress provides a count down and transfer statistics during the copy.
sudo, is used to ensure rsync has appropriate rights to access and read all files on your drive regardless of owner. This also allows rsync to write the files to the new drive recreating the original owner information.
rsync is likely the best choice because it can be rerun in case of problems, offers detailed logging, and is as fast as can be while remaining safe.