drush sql-sanitize: exclude user #1?
There's no such option in drush, all users are sanitized.

As a workaround you can save the user 1 data (or any other user you want) with drush sqlq and restore after sanitization.

Using bash:

user_data=$(drush sqlq "SELECT pass, mail FROM users WHERE uid = 1"| tail -n1)
user_pass=$(echo $user_data | cut -f1 -d" ")
user_mail=$(echo $user_data | cut -f2 -d" ")

drush sql-sanitize ...

drush sqlq "UPDATE users SET pass='$user_pass', mail='$user_mail' WHERE uid = 1"