Sorting users by a field, not by ID

By passing orderby and order arguments in array.

$args = array(
'orderby' => 'login',
'order' => 'ASC',
);
get_users( $args );

orderby – Sort by ‘ID’, ‘login’, ‘nicename’, ’email’, ‘url’, ‘registered’, ‘display_name’, ‘post_count’, ‘include’, or ‘meta_value’ (query must also contain a ‘meta_key’ – see WP_User_Query).

More details : https://codex.wordpress.org/Function_Reference/get_users