i dunno, i am not a fan of juicing, be sure you properly chew your juice to get some enzymes going, i think if you are going to eat veggies just bypass the juice process and chew the veggies and if the fibers are too tough just spit em out
each vegetable has a medicinal purpose though, why are you feeling the need to juice?
celery is excellent for mineralization and also hcl production in the stomach, the leaves have a good amount of chlorophyll which helps to cleanse the blood and systems of the body (i think it makes the helpful microorganisms happy or the others not so much) the bitter i assume would spark the gallbladder and liver into producing some enzymes.
red cabbage has a lot of sulphur which is pleasing to the liver, it is also said to heal the stomach and intestinal lining.
green zucchini is an excellent base, yellow ones are rather sweet, they are generally inexpensive and are said to pull mucus out of the system (i think drinking a juice of it is akin to that broth with the zucchini, green beans...etc....good samaratin posted about it i think i forget he medicinal uses of the broth though)
i would do zucchini, parlsey, and a few celery stalks....kale(chewing the stocks of these is more pleasent though, they are delicious, i spit out the harsh fibers) but not drink(chew) more then 4 oz at a time