Display featured comment using widget on your WordPress site.
Its simple to use, install and activate, then add featured comment widget from Dashboard -> Appearance -> Widgets, fill in the comment’s ID you want to display as featured. It allows you to set Gravatar width in pixels and Comment excerpt size in characters.
One more thing, a brand new plugin Featured Comments is there in WordPress plugin’s repository which provides more useful features but right now its not working and I think it will be working fine may be after next update so keep an eye. It might become more useful for you.
If you also know about any good WordPress plugin that displays featured comment then feel free to mention it here. Sharing is everything.