I suggest working with an independent insurance agentthat works with many carriers. If the agent is any good they will:
Understand your needs and the best policy options given your profile
Give you multiple carriers to compare on prices for you
Help you get discounts based on what you own and their knowledge of carrier applications
There is not one "cheapest insurance company" for everyone. Every carrier has their ideal customer that they are targeting and prices their insurance rates to attract that type of customer and not others.