Plugin for rating comments and polling

Dear WordPress community

I am building a website to blog on a specific topic.

I need the added functionality of visitors being able to post comments and ideas and simultaneously being able to rate other posts on a 1 to 5 scale. These visitors would have to register to do this.

An additional useful feature would be the ability to collate the polls/ratings into an easily digestible format.

I would be very grateful for advice on plugins, widgets and even themes which would be most suitable to achieve these objectives.

My thanks in advance