If you are using myetherwallet, your need to use password will be nil! You really do not need password to unlock your wallet with mew since your coin is not saved on any server, mew only give you access to interact with ethereum blockchain, your password is onpy needed to rap your private key of which you can decide not yo use password!
I use the password and keystore file. I believe that this method is the safest because no one can get my file. even if someone knows my password, he will not be able to enter the wallet without a file
the keystore is very safe but you should kept your private key to explore other options. your account is encrypted so you need password which you have set. probably you need to continuing try guessing your password
