Pat, it depends on what category of cake you like.
For butter cakes, the Domingo I think might be the most moist, but it is rich and denser in texture compared to the chocolate fudge, which is also plenty moist but with a light, fluffy texture.
There is also, of course, the Oblivion custard cake, (flourless).
For a light texture and moistness that comes from water, not butter, try the either the genoise au chocolate or the moist chocolate genoise. These strike me as particularly nice as the weather turns warmer.
And the Bittersweet Cocoa Almond genoise is very moist from all that butter- its texture is more cake-like than the Oblivion but slightly denser than the Domingo.