Display power consumption ratio of smartphones and smart watches
As you previously said, it depends much in which situation your smartphone or smartwatch is at the moment.

In this article you can see some interesting data on power consumption for most parts of a smartphone considering many scenarios:


In suspended mode (scenario in which the smartphone stays most of time with backlight off, but ready to receive call, wifi, etc...) the most power consuming parts are, in order: GSM, CPU and graphics.
In Idle mode (when the smartphone is "awake" but no app is actively being used) almost 50% of the power consumption comes just from the screen (graphics and LCD) considering the backlight off. The GSM (22%) and CPU are the next biggest consumers. 


Obs: Notice that the power consumption of the screen grows exponentially with the brightness level, so you might have different results depending on that factor. As example, In idle state, if the backlight is at its maximum brightness, it can reach 80% of the total consumption.


During a call, the GSM dominates the power consumption, followed by the screen and CPU.


What about an entire day?


In a scenario of an average day where you have to make regular calls,  the main consumers are, in order, the GSM, CPU and Graphics.