LordPretender

Similar to the original native one, this plugin let you define the range of stats to retrieve. 
Also you will be able to add the category name of the post.
Finally, this widget will only display posts (and not pages too). 
This plugin read the top 100 of posts/pages and keep only the X first POSTS (X = number defined in the widget parameters). So, you can have less posts than requested.
Jetpack is required to work. 
A wordpress account and your blog must be linked.
You can find a demo here : http://www.spoils.fr/ 
The widget is named “Articles populaires” on the sidebar.

Jetpack Popular Posts

Using Jetpack stats, this widget will display the most popular posts.

mrpaolo

If you have ever asked yourselves:
<ul>
<li>How many articles per month are published on my website? And how many comments?</li>
<li>Which is the longest articles published on my site? And the shortest?</li>
<li>Which are the most commented posts of the year?</li>
<li>How many words are in total in your post? And on average?</li>
</ul>
Well, then with SiteStats you get all those answers (and much more!) in one place with a beautiful interface.

SiteStats

Provides useful and interesting statistics about your Wordpress website.

Jetpack Popular Posts vs SiteStats