A man who has been up and close with both men has a 100% more perspective than you Joe the fan....lol
Yes your right, I was born in Clinton, LA (google Zachary LA), grew up in New Orleans LA, immediate family went to Grambling and Southern Universities, immediate family lived and played football in Los Angeles, CA, and immediate family lived and played football in the state of Washington attending WU and WSU.
I have had an extremely close perspective on the passing abilities of both Warren Moon (in Los Angeles, college and the pros), and Doug Williams (around Zachary, Clinton, and Greensburg, LA areas, in high school, college, pros, etc.).
Both Warren and Doug were known for the perfect spiral passes. However, Doug had more arm strength.
For all-time pure arm strength, and in order, I would say Williams, Elway and Favre (in Louisiana it is pronounce Fav-ray and in his part of Mississippi its pronounce Far-v but that is a long story). All had a baseball background which I think helps a lot.