The best option would be natural organic yoghurt that is unsweetened and has active yeast cultures. You can add bit of honey or fresh fruit for flavor.
DQ
The question was "what type of yogurt" is best for the Budwig diet and my answer responded specifically to that question.
If one is to use yogurt with the Budwig diet, then organic non-sweetend yogurt would be the best option, and you can use a bit of honey according to Budwig to sweeten it. Another good option would be a bit of fresh organic fruit.
Given the exact question posed I do not see a better answer, do you?
I do not want to mislead anyone about Budwig. I recommend it, or at least elements of it, in my protocol and have a chapter on it in my book - and I admire greatly the work of cancer pioneer Dr. Budwig. However, when it comes to giving the best advice in the Cancer support forum then I have to point out that while the Budwig protocol is a good one, following it strictly may not be the best option for beating cancer.
Others certainly may disagree, but overall success rates say otherwise.
DQ