The below graphic lists the top three polls by average error.
With that said, it's not totally fair to focus solely on results. After all, polls are important beyond just the final results. I'll let Mark Blumenthal explain:
The larger lesson is this: Automated polls have been maligned, unfairly in my view, as inherently "unreliable." Yet when it comes to predicting election outcomes they continue to prove, NY-23 aside, at least as reliable as surveys done by conventional means. In New Jersey this week, they were more accurate in predicting the winner. At the same time, however, it would be wrong to jump to the opposite conclusion and place inherently greater trust in all automated surveys, especially when used for purposes other than predicting election outcomes.Personally, the past two election cycles have increased my trust in automated polling. Their efficiency, higher sample size, and lack of intimidation of the voter seem to have led to their move to the forefront.
Live polls like Quinnipiac still have clearly proven their worth, but one thing is clear - you have to give SurveyUSA, PPP, and Rasmussen their due.