I've used goat milk, dairy cream, buttermilk, yogurt, coconut milk, soy milk, almond milk. I've used them fresh, canned, evaporated, condensed, powdered, etc. I prefer fresh milk whether goat, dairy or vegetable. But I can't tell the difference of the fresh or canned. I can sort of tell the difference when I use powdered and don't like it. The only 'milk' product I didn't care for was greek style yogurt. Made my soap cakey. I prefer regular plain yogurt instead, its creamy like milk and makes a creamy soap.
Goat milk is popular with my customers and some specifically ask for goat. I make more coconut milk as thats my staple milk soap so I sell more coconut. But I like to have a variety as my customers like that they can pick different milks. They always ask the difference and I tell them I can't tell the difference but that one is animal and the other is vegetable/fruit/nut.