I was with Farmers but I wasn't very happy. They were treating me like they were doing me a favor and acting like insuring a small business was a lot of trouble on their part. Just my impression, it might be a great company.
Anyhow, I'm in the process of switching to State Farm. They are giving me a lower rate of $800/year instead of $1100/year and seemed nicer to me. I was an insurance rep for workers' comp for 10 years so I know most of the real quality comes down to the customer service when/if you ever have a problem. And there's no way to find out until the trouble arrives...