The answer depends on your goals.
Boosting a post is generally the simplest way to increase visibility for existing content. It can help more people see a post that is already performing well organically.
Advertising campaigns offer greater control over targeting, objectives, budgets, and performance tracking. They are often more effective when the goal is lead generation, conversions, website traffic, or specific business outcomes.
Businesses should think carefully about what they want to accomplish before investing in paid promotion.
Visibility alone does not always produce results. Strategic targeting and clear objectives usually lead to stronger performance.