I'm in research mode.
I'm reading up on this and have that people will put some of the following in their batters (not all of them in one batter, of course):
These three things are interchangeable. They all contain cultures which help for emulsion but also help for flavor. But each has different cultures so they taste different in the final product and all have different acid levels (buttermilk has the least, sour cream has the most). The more lactic acid, the more you have to adjust your baking powder/soda.
mayonnaise adds an additional fat component and different flavor. Can leave a greasy feel in the mouth.
miracle Whip Same as above
ground almonds I don't see how this would be beneficial at all.
potato starch This doesn't make anything moist. It can help expand your crumb but adding it is SUPER tricky unless you have a recipe that already calls for it.
What is your fave?
I'm trying to make the most moistest cupcakes anyone's every tasted.
If it means putting in anchovies I'll do it!
Sorry, just trying to help again