"The best" is such a loaded question, since it is really subjective. What's best for me may not be best for you and vis versa. But that said, my favorite rating plugin for WordPress is WP Post Ratings Plugin from Lester Chan at GaMerZ.

WP Post Ratings allows you to have a 1-## rating system on your WordPress blog, where you decide how high the rating system can go. You can use the typical 1-5 rating, a 1-10 rating or even a 1-100 rating if you wanted.

You can display the rating of your posts as an image or as text, and the plugin comes with three different image sets to use for rating your blog posts. There is a "star" set, and "bar" set and a "square" set. I use the "square" set here on Blog Strokes.

The WP Post Ratings Plugin uses AJAX to display and allow voting, so the page does not need to refresh when a reader votes on your post.

You can choose to display the voting in your WordPress Theme template files, or you can add it directly into your posts, which would allow you to have voting on some posts, but not all. And there are five distinct customizable snippet templates for the voting sections of the plugin that you can customize to fit your blog.

Finally WP Post Ratings allows you to display the posts on your blog that have been rated the highest, or the posts that have been rated the most often. You can choose how many posts to display for either view, and you can customize the output so that it looks nice in your blog.

Do you use a WordPress Rating Plugin on your blog? Which one do you use and why do you like it better than the others?