What's the best way to describe sensor size?

This marketing image might be the only thing more misleading than the 'inch-type' naming system. The numbers indicated on this diagram are not measurements of the sensor diagonal. It's been nearly twenty years since Phil Askey tried to draw attention to how misleading the industry's naming system for sensor sizes is. Yet the topic still bubbles up from time-to-time, and even manufacturers put out marketing materials that seem confused about it. We hope the majority of you already know that a 1"-...