I believe the juice fast is the best fast because it offers, by far, a wider variety of diverse nutrients through the myriad veggies and fruits juiced for healing purposes than water fasts or the MC fast. With juice fasting you can actually tailor your fast to meet the health issues you're actually dealing with, unlike a water fast or the MC fast.
You cannot tailor a water fast or an MC fast, because all you have for a water fast is water and all you have with the MC is lemonade and maple syrup. With juicing you have an unlimited source of produce to juice for healing purposes. And you can choose to juice which veggies or which fruits that would best heal your ailment. You can't do that with the other two.
All three fasts are excellent tools for health as they all trigger the body to detox the nasty gunk, but juice fasting is the only one of the three that continuously offers a plethora of diverse nutrients, enzymes, minerals (through veggie broths) etc. Yes, the MC fast has some nutrients and minerals through its lemonade and B grade maple syrup, but not the huge variety juice fasting does. As a result of this, juicing gives one more vitality and energy to carry on, than the water or MC fast.
Here are the reasons why I prefer juicing over water and the MC. Someone on the Juicing forum asked why one juices, and this was my response: