What is the best plugin to share the post immediately after its publishing?
You should go with Blog Tool, Publishing Platform, and CMS here many plugins are available. From their i will suggest you should try WP Social Sharing.WP Social sharing adds very attractive responsive social share buttons of Facebook, Twitter, Linkedin, Xing, Google+ and Pinterest to wordpress posts, page, media or any custom post type. This is very lightweight and simple social sharing plugin. This plugin provide option whether you want to include plugin CSS/JS or not. Most of the social sharing plugins uses images/api to display social share buttons, but this plugin created large social sharing buttons using CSS3. Also these social sharing buttons are responsive. For device width less than 480px these buttons converted into their respective icons.Plugin FeaturesSocial sharing support for Facebook, Google+, Linkedin, Twitter, Xing and Pinterest.Auto display to Post, Page, Media and Custom Post type.Custom Social Button text.100% responsive.Reorder Social icon order easily.No Image, button created using CSS3. For device width less than 480px, this plugin used one single image to display social icons.Provide Shortcode, can integrated with any theme easily.Add text before share buttonsThanks