There are a few differences which separate independent agents from buying insurance directly from a national company. Both methods have advantages and drawbacks that have to be considered, and you should also check the financial ratings of any companies you are considering before you purchase a policy.
A national insurer can "travel with you" if you move to another location, as long as the company is licensed in that state, but a local independent insurance agent, even though he offers policies from national companies, may not be able to serve you after the move. Because insurance is licensed and regulated by each state, your current insurance company may not always be the best choice when you go somewhere else.
The biggest advantage to using an independent agent is twofold: the prices are often lower, and you can get a much larger range of options. The reasons is because a national company only offers a limited number of options, while the independent agent is able to shop between many different insurance companies to find the product you want at the lowest price on the market.
Another option is to buy from an independent online agent or broker. This method of buying insurance has the same advantages as a local independent agent along with the portability of a national company with reach into most of the United States. Additionally, buying online means you can shop for insurance at your leisure customize policies to meet your individual needs, and instantly see quotes that compare multiple insurance companies from a single website.
Before you buy a policy from any insurance company, check the company's financial ratings with a company like the A.M. Best ratings company. By limiting your insurance purchases to highly rated companies, you minimize the risk that your insurance company will fail in the event of a sudden increase in claims such as might come after some major weather phenomenon.