I'm one shave from finishing my first jar of Nancy Boy, so I wanted to give a shout out what I think is the best shaving cream for straight razors (ironically, given the name). I've got (or used up) JMFraser (also great with straights), Castle Forbes Limes, Speick, GFT Rose, Lime, Almond and Violet, TOBS Mr. Taylor, Rose, Almond, T&H Ultimate Comfort, AOS Lavendar, Proraso, Musgo Real, C&E Nomad and SAO.
For me, the best shaving cream for straight razors has been without question Nancy Boy. The others are great too. Soaps are a different animal so I won't compare.
But if you havent tried Nancy Boy I recommend it.