I find the bottom left to be a very inconvenient spot due to the palm creating false touch events. Logically, it makes sense to be on either of the left corner

I find the bottom left to be a very inconvenient spot due to the palm creating false touch events. Logically, it makes sense to be on either of the left corners because obviously having it in the middle of the screen (even on the side) takes up valuable content real estate. Between the top and the bottom, I'd pick the top every time. As for ACTUALLY going back a screen, the gesture to swipe from the left is the real UX default. The top left button is for newbies/redundancy.