I know I've mentioned some of the "vintage" soaps before, but I just had to express my respect for the quality of lather that you can get out of these things. I have a puck of the Colgate/Palmolive Barber soap from the 8-puck 1lb pack which has proven to be some shockingly amazing stuff, but until last night I hadn't tried the newer Cup Soap from them. For a buck I couldn't pass up giving it a go. The box doesn't have a bar code so my understanding is that it is pre-1970's and the ingredients are very short:

Soap (not exactly sure what constitutes "soap," but from the performance there's tallow in there), water, fragrance, stearic acid, titanium dioxide, stannic chloride

The puck was NOS but had become a bit desiccated with time so I tossed it into my mug and submerged it in warm water for about 15 minutes. Once that was done I poured out most of my water (still leaving quite a bit though) and went to town with my well soaked Omega 10049. A relatively short load time produced a good amount of extremely slick and cushiony lather. No scent at all of course, not sure whether it may have had some at one time or not though.

TLDR If you find some of the older soaps for a good price, give them a chance even if they look like mummified urinal cakes. I've used Colgate/Palmolive, Tallow Williams, Yardley, and a few others with excellent results. And if you have some you don't use... hit me up lol!