USAA only sells policies to current and former members of the military and their families and is consistently rated at the top of its class by A.M. Best with an A++ financial strength rating. It doesn’t have an official customer service rating with J.D. Power, but USAA is noted by J.D. as providing “claims satisfaction and shopping satisfaction”. A perk of USAA is if your uniform is damaged or stolen in an event your policy covers and you are on active duty or deployed, USAA will reimburse you without you having to pay a deductible.
The cheapest car insurance, period, will likely carry the minimum coverage required in your state. In most states, this is liability insurance only, which covers property damage and medical bills for others due to accidents you cause. Some states also require uninsured and underinsured motorist coverage, which pay for your injuries or damage if an at-fault driver doesn’t have enough insurance.