You know, soy milk has some bad things too...mostly it is made from gene manipulted soy, and that is very bad for you.
An alternative is almond milk. There is some available that is sweetened with Steevia, a low cal plant based sweetener.
The best alternative, IMHO, is home made almond milk. all you have to do is soak almonds over night in water, then put them with water in a blender. If you want, you can strain them, but you don't have to, as the almond pulp is good for you.