Where should be installed the fingerprint scanner smartphone?

Fingerprint scanners in smartphones no longer a luxury, they are already well set in the budget model. The basic layout is two in front, below the LCD and behind the camera (or near it). Sometimes there are at the sides, like Sony smartphones. Some manufacturers have adapted them to perform additional functions. Engineers are actively working to integrate the finger scanner directly “into the screen”, but until that happens we decided to ask our readers which of the available options of accommodation most comfortable. Perhaps there are exotic options, which we forgot. Write your options.