You won't find a better app than this powerful widget flashlight
Flashlight Android Widget Flash - Mundoapp
With this powerful tool you can replace the basic flashlight that Android offers you, with the option of adding it as a widget to the desktop and to the top bar.
It has features such as: Flashlight, Widget, Flashlight on screen, SOS function, Flash speed, among others.
Give it a try and you won't be able to stop using this handy widget.