Hi Katie -
To quell confusion on any matter concerning food and nutrition, I recommend thinking of things in terms of a continuum that goes from best to worst.
For example, in the case of almond milk your best choice would be to make it yourself -- which is actually surprisingly easy. Just soak almonds over night, peel off the skins, place in food processor or blender and add water until you have reached the desired consistency.
It will last for a few days. Or you can make up a big batch and vacuum seal it in Mason jars (FoodSaver is the vacuum sealer I recommend) and it will last for up to 2 weeks!
If you like, you can sweeten it with a few drops of stevia, or a little bit of brown rice syrup or agave -- much better choices than cane sugar.
Your worst choice on the other hand, would be the most highly processed almond milk that contains added, concentrated sweeteners, poor quality oils, emulsifiers, etc. Check labels to see what's in it.
Some brands will be better than others and you may also be able to find fresher, more "homemade" almond milk in the refrigerated section in glass bottles - a much better choice than what comes in the boxes -- if it's not overly sweetened! Once again, check the label.
Rice milk does tend to be very processed, contain poor quality oils and be very sweet -- although sometimes, depending on the brand, they do not contain added sweetener. The sugar content reflects the naturally occuring sugars from the rice. In general, I think this is a better choice than added, concentrated sweetener such as cane juice.
Bottom line is, unless you make it at home yourself or are able to get fresh, more "homemade" versions in glass bottles at the health food store -- all the non-dairy milks are processed foods and better kept to a minimum.
Try making some almond milk yourself. It's fun and delicious. You might also like to consider other choices for breakfast that don't require a "milk."
Hope that helps. Be well,
Kelly