[SARAFIL]

I've been in the business for a while now. Bottom line, shop around and do so every 2-3 years as things are always changing.

Generally, Geico or Progressive will be cheapest but also generally have worse service when/if end end up filing a claim. They're more likely to nickel and dime you.

Beyond that, it's up to you how you prefer to buy... Direct or via an agent. I'd recommend at least talking to an independent agent and see what quotes they can get you. They are not tied to one individual carrier like exclusive agents (ex. State Farm, Allstate, Nationwide) so they can shop 5-6 carriers to get you options. These are also typically companies that don't sell direct so they can access companies you aren't seeing if you shop online yourself.

A few things to beware of...
A) do you insure your home with the same company? If so, you're probably getting a discount on both policies that you'll lose if you switch just your auto. May be worth asking an agent to quote both for you, since you might also be overpaying for home insurance anyways.
B) beware of "disappearing discounts" - these are things like early shopper, new client discounts, etc. They roll off over time so your rates will go up without even factoring in general rate increases. It causes some people to feel like they are getting a bait and switch after a year.

Pricing insurance is tricky because it's all about making a prediction about future losses with limited info. Carriers use many variables about you and set rates based on their historical experience. The huge rate differences you see on quotes are actually very common just because you are getting segmented differently by each carrier because they use different variables to price the policy, and one might group you into a preferred bucket while looking at a different set of variables you might not be as preferred by another carrier. That's why you should always shop around every few years.