There is not one best place to put your safe. The placement decision should be based on the contents and how frequently you want access to them, the type of safe, and how heavy the safe is.
Safes and vaults that hold items that you’ll be accessing frequently should be placed near to where those items will be used. The safe won’t offer you much protection if you don’t use it because it isn’t convenient. A home safe used to secure jewelry should be placed in the master bedroom, bathroom, or closet. It’s also a good idea to place the safe on a pedestal or reinforced shelf to bring it up closer to between your elbow and shoulder height for easier access. If you intend for the safe to hold guns for an emergency you will likely want it in your bedroom as well.
If the safe is for valuables you don’t need to access frequently, then the location is less critical. An out of the way spot will work, such as an unused closet or the garage. Safes that secure guns or hobby collections can be placed in the garage, office, spare bedroom, a closet or even the family room.
Fire safes used to secure documents perform best when placed on a cement floor or against cement walls, making the garage or basement an ideal place if you want to secure important paper items such as cash, stock certificates, wills, legal documents, contracts, etc.
The weight of your safe is a factor in placement. Generally safes under 1,000 lbs. can go on a second floor. Safes heavier than 1,000 lbs. should be placed on the ground floor. You may need to make special accommodations for one of the heavier safes if your home has a raised foundation. Be sure to consult an expert to make sure you have chosen an appropriate location.