I talked to Erie when shopping around a few years ago and Nationwide had them beat by a good amount. I chose Nationwide and have had very good luck with them. My truck is $5 every 6 months.
If you are going to get hit by anyone, make sure they have State Farm. They paid for a complere back half of my altima when I was hit 2 years ago. I took it to the dealer and they wrote up just about everything that could be replaced and painted, and State Farm just cut a check to them. I was told State Farm is the best company to have, but I really hate their agents and the amount they charge.