One thing I noticed between USAA and another company (recently bought a house/purchased homeowners insurance) was that the number USAA used for the replacement value was VERY high, I think the quoted 190,000 to replace my house, whereas the other company used 135,000 (which is more realistic). I dont know if that has much of an affect on the premium, but it's something to notice.
This is probably to make sure you insure your home to @ least 80% of its value. If you do not, the insurer will not pay replacement cost for the repair/rebuild (if you have replacement cost coverage). I know USAA uses software to determine LKQ (like, kind, quality) of a dwelling's rebuild cost.
Although there may be a cheaper insurer than USAA, you get what you pay for when it comes down to claim time and service.