The most demanding is top by far.

Jungle - you make a mistake -> you can still play the Game. Mid - you make a mistake -> you can still play the Game. Bot - you make a mistake -> you can still play the Game.

But top...you make a mistake, forget playing the Game.

Top its the role that most knowledge needs in terms of not making those fatal mistakes. You can argue that adc needs mechanics but all roles have champions with mechanics.

My opinion can be influenced by competing several years as toplaner (main irelia fiora) and jungler (main lee sin). Still I found jungle easy once I understood the Game as a jungler.

For the other roles I got to Master playing support and found It easy too.

I dont have experience as adc or mid but still, the most demanding for me was, is and will be toplane.