Well, in choosing insurance, I would focus more on how the companies you work with handle claims than what they charge as a premium.

I have 6 of my 8 boats insured with Nationwide. (the other two are uninsured - they're not sailable at the moment). They have not been the cheapest but they have treated me well every time I have had a claim. That said they are in the process of converting me over to one of their subsidiaries so I don't know what the future will hold.