1. Condition: The condition of a coin is one of the most important factors that determine its value. A coin in mint state (MS) or uncirculated condition will be worth significantly more than a coin with wear or damage.
2. Rarity: The 1927 S Peace dollar is a relatively common coin, with a mintage of 1,050,000 pieces. However, it is still considered to be a desirable coin among collectors due to its historical significance.
3. Mint Mark: The "S" mint mark indicates that the coin was minted at the San Francisco Mint, which adds some additional value to the coin.
4. Eye Appeal: The overall eye appeal of a coin is also taken into consideration. This refers to the coin's luster, color, strike, and any other aesthetic qualities that add to its appeal.
Given these factors, the value of a 1927 S Peace dollar can range from a few dollars for a heavily worn coin to several hundred dollars for a mint-state or proof coin. It is always recommended to get an accurate appraisal of a coin from a reputable dealer or numismatic expert to determine its exact value.