Here's some things Samsung could fix quickly and easily I would think
1. Add seconds to the taskbar time HH:MM.ss display instead of just HH:MM Having the seconds display also is great for quickly counting something rather than opening up the whole phone to start the stopwatch/countdown timer.
2. Find a better way to activate the light Motorola has 'chop chop; to turn it on, OnePlus you can draw a gesture V on the screen when off to activate the light. Samsung I have to swap the camera for the light as a Gesture or open up the phone and select light. This is tedious. OnePlus also lets you create your own gestures (why can't we do that Samsung?)
3. PLEASE PLEASE PLEASE fix this one On motorola, Oneplus, just about any other Android, you can select "Ask" for SMS sending (dual sim). On Samsung it's locked to one SIM at a time - why???!!!! Please make the option "Ask" for SMS sending, exactly like it is for Phone calls. I want to be able to select the SIM when sending an SMS via a pop-up, just like I can when I make a call and it prompts me. It's there already for calls, give the same flexibility for SMS sending please
