房屋保险问题请教 - 先谢了！

I am getting insurance bids for my primary and rental homes. The insurance agent asks me the dwelling cost, which she explains this is the cost for reconstructing your home in case of accident. I give her county appraisal amount, she said it is low. and she came up with a number which is way higher than the county appraisal. Her calculation is based on square footage mainly.

what is the appropriate for dwelling cost? also she said I can either choose replacement cost or actual cost for dwelling cost. which one is good choice?

your help is greatly appreciated.