I am afraid there IS no definitive answer.
My understanding is that Professor Taylor only used the Optifast Shakes because they were sponsored.
If you want low carb, then you can look at Almased or Atkins. Almased has a lot fewer chemically ingredients.
Beyond that, you can pick any of the various diet shakes, depending on whatever criteria you like.
Most of them will end up giving you a lowish carb intake across the day - simply because they are low calorie, but if you are sensitive to carb highs and lows (like I am) then I would go for the lower carb end of the range.
The other alternative is to go the Real Food Route, which is to take the allotted number of calories for each meal, but eat actual food. Much more hassle, but much better for you, I imagine.
(have to admit my bias, at this point: I prefer Fasting to diets like the ND, but that doesn't mean I don't totally support your decision to go the ND route
)
Hope that helps!