The term "most transacting" can be substituted with several other words and phrases, depending on the context of the sentence. For example, one could use "top-selling," "highest-volume," or "busiest" to convey a similar meaning. Other synonyms could include "most popular," "best-selling," "top-performing," or "leading." The choice of synonym may vary based on the specific industry or product being discussed. In general, the use of synonyms can help to add variety and depth to a piece of writing while keeping the message clear and concise.