I don't like going with a multiline insurance company that underwrites Property, automotive, RV's and boats in a single policy. They tend to be jack of all trades. I also don't like direct-line insurance (e.g. Geico, Progressive) There is no competition.
I prefer going with an independent agency that represents a variety of insurance companies. They will be able to negotiate the companies to find the best policy for my needs.
For the boat I choose to do business with an independant agency that only writes marine policies and represents a variety of insurance companies. Many of those insurance companies only underwrite marine policies.
https://maritimeinsuranceinternational.com/