Rice milk has been made for centuries, as many cultures didn't have access to cows but had tons of access to rice. :) This product is pretty darn close to the original concoction or I wouldn't recommend it.
goat's milk is fine too, especially if it's raw (unpasteurized).
Kefir would work too. it would probably taste darned funny, but it would work. ;) Coconut milk too - yum!!! or almond milk, all of which can be made from scratch, as can rice milk.