I found out the best way is rsync.
$sudo rsync -avE SRC DEST
does the trick. Only copies newer files, so even if you want to cancel it in middle of job, or if new files were written after the copy, it will pick up those newer files only, and start where it left off.
-a set the archive bit. sudo is necessary for the archive bit part.
-E preserve metadata (even the color of the file)
and you can use finder to drag in the folders into the terminal window for paths (especially if they have spaces in them)
There. I documented it. Most likely for me, 5 years from now.