You can display users by the number of comments using the following code. Just add to the Function.php file

function top_comment_authors($amount = 5) {
global $wpdb;
$results = $wpdb->get_results('
    SELECT
    COUNT(comment_author_email) AS comments_count, comment_author_email, comment_author, comment_author_url
    FROM '.$wpdb->comments.'
    WHERE comment_author_email != "" AND comment_type = "" AND comment_approved = 1
    GROUP BY comment_author_email
    ORDER BY comments_count DESC, comment_author ASC
    LIMIT '.$amount
);
$output = "
"; foreach($results as $result) { $output .= "

".$result->comment_author."
"; } $output .= "
";
echo $output;
}

The withdrawal of users is carried out by calling the function: