Armstrong and Langford have no case for top 4 in any given weight class by my criteria but they are both in my top 4 p4p.
I think you could reasonably include Fitzsimmons there if you were so inclined. Armstrong makes quite a few peoples top ten at both light and welter ,where he made 18 successful defences.
Floyd is at or near the top of 130lbs all-time, as well as being somewhere in the 10 -20 p4p all-time.