The optics aren’t good but a long drop hanging probably minimizes pain vs either lethal injection or the chair.
The Soviets had an excellent method, maybe the Russians still use it. Prisoners were never told when death was coming—no special meals or padres. Death row was a cell with a drain in the middle of the floor. One morning, the guards came in, made you kneel over the drain, and blew your brains out. Remove the body, hose down the room for the next occupant. I once read they had people on death row for extended periods of time until one day the decision was made to execute them the next morning. Very efficient if it was truly what they did.