DCoda

This plugin is only supported on PHP 5.2 or greater.
 
ExportReaders easily allows you to export your users details for use elsewhere. 
Just select the roles you with to export and set the criteria to select the commenters and download its that simple. 

If you are having trouble and cannot find the answers in the <a href="http://exportreaders.dcoda.co.uk/help/faq/" rel="nofollow ugc">FAQ</a> you can post your support questions to the <a href="https://wordpress.org/tags/export-readers" rel="ugc">WordPress Support Forum</a>
If you find ExportReaders useful please rate it at <a href="https://wordpress.org/extend/plugins/export-readers/" rel="ugc">wordpress.org</a> and please consider making a <a href="http://exportreaders.dcoda.co.uk/donate/" rel="nofollow ugc">donation</a> to help us set aside more hours to maintain ExportReaders
ExportReaders is written by <a href='http://dcoda.co.uk' rel="nofollow ugc">dcoda</a>
You can check out our other plugins <a href="https://profiles.wordpress.org/users/dcoda/" rel="nofollow ugc">here</a>
If you require a custom plugin you can contact us <a href="http://dcoda.co.uk/contact/" rel="nofollow ugc">here</a> and maybe we could write it for you.
<h3>Copyright</h3>
(c) Copyright DCoda Limited, 2007 -, All Rights Reserved.
This code is released under the GPL license version 2, available here:
<a href="http://www.gnu.org/licenses/gpl.txt" rel="nofollow ugc">http://www.gnu.org/licenses/gpl.txt</a>
There are so many possibly configurations of installation the plugin can be installed on we limit testing to a PHP 5.2+ Linux platform running the latest version of WordPress at the time of release but it is released WITHOUT ANY WARRANTY; 
 without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

ExportReaders

Selectively export all your reader details ( users and commenters )

Toro_Unit (Hiroshi Urabe)

hamworks

Simple CSV Exporter. Exported CSV can be imported with <a href="https://ja.wordpress.org/plugins/really-simple-csv-importer/" rel="nofollow ugc">Really Simple CSV Importer</a>.
When you select a post type, the posts will be exported.
Github Repo: <a href="https://github.com/hamworks/simple-csv-exporter" rel="nofollow ugc">https://github.com/hamworks/simple-csv-exporter</a>
<h4>Customize the data to be exported</h4>
Customize for column.
<pre>use HAMWORKS\WP\Simple_CSV_Exporter\Data_Builder;
add_action( 'simple_csv_exporter_created_data_builder', 
 function ( Data_Builder $data ) {
 // Remove column.
 $data->append_drop_column( 'page_template' );
 // Add custom field column.
 $data->append_meta_key( 'my_meta_key' );
 }
);</pre>
Customize posts for export.
<pre>add_action( 'simple_csv_exporter_data_builder_for_wp_posts_pre_get_posts', 
 function ( WP_Query $query ) {
 $query->set( 'order', 'ASC' );
 }
);</pre>
Data filter for metadata.
<pre>add_filter( 'simple_csv_exporter_data_builder_for_wp_posts_get_post_meta_fields',
 function ( array $fields ) {
 foreach (
 array(
 'your_flag',
 ) as $key
 ) {
 if ( isset( $fields[ $key ] ) ) {
 $fields[ $key ] = ! empty( $fields[ $key ] ) ? 'TRUE' : 'FALSE';
 }
 }
 return $fields;
 }
);</pre>
Data filter for post.
<pre>add_filter(
 'simple_csv_exporter_data_builder_for_wp_posts_row_data',
 function ( $row_data, $post ) {
 $row_data['permalink'] = get_permalink( $post );
 unset( $row_data['comment_status'] );
 return $row_data;
 },
 10,
 2
);</pre>

Simple CSV Exporter

Simplicity is the key to a powerful tool.  This is the sister plugin of Really Simple CSV Importer, and both do a remarkable job of manipulating post data in and out of the DB. 

The one thing missing is the ability  to export other types of data, users, taxonomies, attachment meta-data...it would be a real complete swiss-army knife with the ability to also export these other data types.  This way you can batch fix missing pieces of meta-data in your DB by simply sorting through it in a google sheet

ExportReaders vs Simple CSV Exporter