7. Adam Lambert: He may not have sold as many records as any of the previously mentioned stars, but the season eight runner-up has a huge advantage -- he was on the show. Indeed, Lambert's Idol run was consistently spectacular, drawing in legions of now diehard fans still grieving that year's results, and he worked the competition flawlessly. What Idol hopeful wouldn't welcome the insight, not to mention Lambert's genial manner, during the most stressful opportunity of their life? Now that's a judge worth tuning in for.