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.

maxpagels

Most Popular Tags is a WordPress plugin that allows you to display your blog’s most popular tags or categories as a sidebar widget. The plugin takes advantage of the new Widget API introduced in WordPress 2.8, allowing multiple instances of the same widget, each with it’s own unique configuration. You can specify how many tags/categories/link categories to show, the size of the smallest and largest ones, which unit and format to use as well as advanced ordering options.

Most Popular Tags

Most Popular Tags is a plugin that displays your WordPress site's most popular tags, categories and custom taxonomies as a sidebar widget.

Jetpack Popular Posts vs Most Popular Tags