Machine counting is more reliable. Advantage to the Bush team. Hand counting is more valid. Advantage to Gore. The Gore team has the better argument.
Reliable instruments give consistent scores with narrow margins of error.
Valid tests yield the information that one is seeking. IQ tests are certifiably reliable. That is a very controversial question. True-False and multiple choice tests are unquestionably more reliable than essay exams. Punch-cards machines reliably tabulate whether or not a laser beam has passed through a hole in the card.