Think about it. How many times have you been in a hurry to get out the door to work or an appointment and left your keys inside the house? How many times have your children lost their house keys at school or while playing? We all forget our house keys from time to time and calling a locksmith or breaking the lock can be quite expensive. Most people will hide a key under a doormat or loose stones near the door for those times when they need to get in. The problem with this is that most thieves know the entire obvious hiding place and when they find the key they are in the door in seconds.
The solution to this problem is to use a key safe to hide your keys. The means that even if the thief finds the key safe he or she will have more problems opening the safe then they would just kicking in the door and the noise they will make doing either will probably attract attention and will certainly take more time just getting inside than most thieves want to spend. The best key safe is the one that is small enough to hide if necessary and strong and difficult enough to open to make it impossible to do without a lot of noise and time.
The best key safe will also have at least two ways to open it, some operate with just a single key, which can be lost or forgotten also. These cheap designs are probably a waste of money, while the more expensive ones will include both a combination, preferably digital and also have a key access. These safes can be set to require one or the other or both.
You can find the best key safe for your needs at most hardware stores and the internet has a wide variety. You can buy one; a basic model, for about $40 and the better ones can go as high as $200. Buying a key safe box in the middle of this range is probably your best bet.