I would prefer optional lecture. If the grade you receive is pass as long as you pass, that eliminates most of the anxiety and unhealthy competition with respect to grading, regardless of whether you're ranked. Your pre-clinical performance affecting your eventual class ranking seems to be too abstract and removed from your day-to-day life to stress you out much. Letter grades are stressful because we've been conditioned from pre-med to believe that receiving less than an A- is bad and will jeopardize our desired future as physicians. But in a med school, only a minority of a class with mostly historically A students will receive As, if the classes are graded on a letter system. Optional lectures, however, greatly reduce stress and increase enjoyment of medical school. Being able to sleep-in and study at one's own pace significantly improves quality of life. I remember in undergrad forcing myself to go to lecture way too early in the morning, retaining very little and eagerly awaiting the lecture's conclusion, because attendance affected my grade and/or testable material was only covered in class and not posted online. I would have liked those classes more, and likely would have done better, if I could have watched the lectures online when I was ready and alert, with the ability to pause and rewind.