Halon
In addition to the solid research on the subject, I can only provide an anecdotal example of why I have chosen Halon for my RV and Cessna, in addition to the above post about the discharge of large amounts of Halon in an enclosed space having no ill effects on those present.
In my airline career, I have, as have other professional pilots, spent many hours inside an isolated sealed box on hydraulic stilts full of electronics prone to typical aircraft fire hazards, totally isolated with no access to real supplemental oxygen, along with the other pilot and the instructor, commonly called a full motion flight simulator.
Those are protected from fire by massive fire bottles in the simulator bay, filled with Halon, which I doubt would be put there by those who design those things if there was a real risk to the humans inside.
There is no fast escape from flight simulators when they are in use, and it would be impossible to evacuate before the simulator was filled with Halon if a fire were to break out.
Modern advances in fire suppression technology may offer other even better solutions, but Halon is a proven product that does not adversely affect humans in typical uses.