Galaxy S5 and other accessible gear are a perfect fit for you if you have that much of a budget. If you employ your phone to save sensitive data then you must stretch your pocket so that you can make sure the information within your device is safe. If you are sure that you have generated a password which is impossible to think of and no one can open and leak the data you preserved inside, then you are secure. You can go for a usual smartphone and continue keeping your secret documents in it, at least until the time it gets open for all. Otherwise, you can choose another device which is quite costly, but you will feel more protection with it.