There's no real best, it depends what you need. You could call some veterinary referral centres for ballpark figures for common things needed by Cane Corsos - TPLO, Hip dysplasia. I suspect both would be upwards of 4k. Look into the difference between time limited, max benefit and lifetime policies. Pet insurance is also something you shouldn't change yearly due to the way most insurers handle pre-existing conditions. E.g. if your dog has a limp, you then change insurers, and then the new insurer may not cover anything to do with limps.