The only state the I know regulates insurance is Mass. A state insurance board sets the rates, and only allows companies to petition for rate raises annually. Every driver pays the same rate, subject to specific deductions for good driving, no tickets etc.
So it really doesn't matter there which company you chose. Some companies won't even sell policies in Mass - I'd guess because they can't raise rates, and can't make enough money.
IF insurance is mandatory - which is true in most, if not all states - then it should be regulated as well. AND, yes, it should be mandatory, so we do not become victims of the uninsured. Of course, even mandatory here in Florida, there is still a "fee and choice" for uninsured motorist coverage, and based on the laws there should be none of those ... right? Don't bet on that one.