What is the best oil to use when cooking in a wok?
Frying in a wok doesn't necessarily imply a single particular oil for all foods you cook. It may vary up to the ingredients, the technique (yes, there is more than one wok technique), the recipe, personal preferences, price etc. 

As a general rule, as you've mentioned in your question, wok techniques require relatively high temperatures so oils with reasonably high smoking points should be preferred, for sure. Depending on its type and the temperature you want to reach, peanut oil may be or may not be suitable for the task.

This table and this list reveals that peanut oil is not the one with the highest smoking point and there are significant differences between the smoking points of the types of peanut oils.

As a result, I don't think that a "best oil" can be named, but I believe -some type(s) of- peanut oil would be fine for many purposes --and it is a must for some recipes. Still, some other oils can be used in the light of what I mentioned above. For example, I prefer sunflower oil in many cases.