Automattic

John Godley

Donncha O Caoimh (a11n)

Eoin Gallagher

Lenny

Future upgrades to Sharedaddy plugin will only be available in <a href="http://jetpack.me/" rel="nofollow ugc">Jetpack</a>.
Jetpack connects your blog to the WordPress.com cloud, <a href="http://jetpack.me/support/" rel="nofollow ugc">enabling awesome features</a>.

Sharedaddy

Future upgrades to Sharedaddy plugin will only be available in Jetpack.

Nick Halsey

This plugin, like many others, adds content-sharing functions after your posts (and optionally pages and media attachments). But the similarities end there.
QuickShare is quick because it doesn’t run 3rd-party sharing JavaScript; in fact, there is no front-end JS. The sharing functions are built into links that take the user (in new tabs) to the native sharing interface on each social media site.
You can choose which social media sites to include from: Facebook, Twitter, Pinterest, Linkedin, Google+, Tumblr, Reddit, and StumbleUpon. A basic email function is also available.
The share bar appearance is highly customizable and share functions can be displayed as either icons, Genericons or text. Each display method features different customization options; customize through the settings page or with custom CSS.
QuickShare can be displayed at the end of ever post, page, and/or attachment, or all post types automatically. Or, you can use the <code>[quickshare]</code> shortcode to display QuickShare wherever you’d like in any of your posts/pages. You can also exclude posts by id, or even use a custom output function in your templates, including the ability to override the default generated sharing data.
As a bonus, QuickShare includes several built-in CSS3 effects for hover state animations.
Please visit the plugin support forum for help with custom css snippets and/or feature requests!
Please note that QuickShare does not and will not support link tracking, because of its goal of being simple and lightweight. You can use a 3rd-party tool like Google Analytics to track shares as external links.

QuickShare

This plugin, like many others, adds content-sharing functions after your posts (and optionally pages and media attachments).

Sharedaddy vs QuickShare