*Yahoo! owned micro-blogging platform tumblr is used by millions of people across the world. With over 183 million blogs and 83 billion posts (tumblr posts are similar to Tweets) tumblr is ranked as 35th most visited website in the world by Alexa.
*The functionality of Plurk is similar to Twitter but with certain modifications.
According to my expertise, Instagram is the best alternative to Twitter.
This is because Instagram provides various kind of features to the users for both personal & professional uses. And Instagram has the capability to generate more website engagement ratio, increase website conversion rate, bringing more & more customers and driving more website traffic.