This depends on what the purpose is. For insurance purposes it may be one price, for tax purposes it may be a different price, even an appraisal may be a different price, but assuming you want to list your home for sale the best way to determine the price is to contact a real estate agent and ask for a CMA (Comparative Market Analysis).
A CMA takes in consideration many factors. The location of the house, the recently sold homes in the area that are a fair comparison to the property, the market conditions which are determined by looking at employment rates, interest rates, income rates, and home inventory, then the condition of the home is considered and of course adjusting for what amenities the home has.
The way you do not determine a homeâ€™s market value is by what you owe, how much you want to put in your pocket, or how much you have put into the house. Just because you spent $20,000 on an in-ground swimming pool doesnâ€™t mean your house is worth $20,000 more.
I hope this answer is useful to you.