The saddle needs to be wide enough to support the sits bones and not much more than that. This width will change depending on how far forward you're leaning. You need a wider saddle to sit upright than to race.

I prefer a fairly flat topped saddle 140-145mm wide with some drop to the nose. Not that this info helps you, but it gives you an idea of what can be quantified.

For me the worst saddle ever invented was the hugely popular Concor. That thing exactly wedged itself between my sit bones and tried to wedge them apart while jamming itself into my crotchular stuff.