Which adjective would best describe an overly complex and grand style of writing that actually lacks genuine content?

The adjective "bombastic" is the most fitting choice to describe a style of writing that is overly complex and grand but lacks genuine substance. Bombastic language is characterized by the use of inflated, extravagant expressions that aim to impress rather than to communicate clear ideas. This type of writing often employs a high level of vocabulary and rhetorical flourishes but fails to deliver meaningful content, making it sound superficial and pretentious. As a result, writing described as bombastic may be visually impressive but ultimately lacks depth and clarity.

In contrast, the other options—such as "simple," "clear," and "effective"—suggest qualities that are typically associated with straightforward and impactful communication. These terms imply a lack of complexity or exaggerated style, which does not align with the description of writing that is grand yet devoid of real substance. Therefore, "bombastic" distinctly captures the essence of writing that is showy without being meaningful.