The phrase "most argued" refers to something that has been heavily debated, discussed or disputed. There are many synonyms that could be used to convey a similar meaning, such as "controversial," "hotly debated," "highly contested," "heavily disputed," "much disputed," "vociferously debated," "widely discussed," "disputed," "much debated," "much talked about," "the subject of heated discussion," "object of controversy," and "a bone of contention". Depending on the context, any of these synonyms could be used to describe a topic or issue that has generated a lot of disagreement or conflicting viewpoints.