How about we lock you outside with no access to AC or heating for a few days and see which is more survivable. I'll pick 40 every single time if it's not wet. Wetness complicates the situation slightly as choosing between hypothermia and dehydration / heat stroke is a tough one, but you can at least dress for cold and wet.
My honest criteria is more complicated. The worst is really anything between 32 and 50. If it were up to me I'd skip the months with average temperatures in that range. I'll maybe appreciate a sunny day in the upper 40s in late February or early March if the snow is all melted anyways.