It does seem odd to compare rates without having a detailed list of all the policy factors that drive rates to have a more apples to apples comparison: deductible, rental car coverage, policy limits, zip code, parking situation at night, types and ages of vehicles insured, mileage driven each year, number of and age, gender, years of driving experience, and record of each driver, whether bundled with other policies, types of discounts offered/qualified for...to name a few.
Every few years I shop around to see what I rates would be for home, auto and umbrella. Consistently Liberty Mutual and Travelers Insurance come out ahead on rates. Experience with Liberty Mutual has been good so I've stuck with them. Although this thread is a good reminder for me that is about time to and shop the rates again to see if I'm still getting the best rate.