denimblue's former flagship device, the LG G2, is the first Android smartphone to come with DT2W.
No wonder he will miss it.

This is an extract from an article I read.....
"The LG G2, the company 2013 flagship, was the first Android device to get the double tap to wake/sleep feature as default. Since then, most of the LG devices, whether entry-level or top-end, come with the novel feature.
The OnePlus One and Asus's ZenFone 2 smartphones also support double tap to wake/sleep feature straight out of the box.
Many apps are also available on Google Play Store that allows the feature on Android devices; however, these apps require root access.
The feature is very handy but it is not native to Android operating systems until Android 6.0 Marshmallow. It will be handy for Android if Google brings the double tap to wake/sleep feature to its upcoming software updates."