Is it better to do more reps and less sets, or more sets and les reps?

it depends on what you are trying to accomplish. Endurance is longer amount of time and lighter weight. Shortening up the reps and more weight is a build or strength mode depending upon the weight etc. You have to look at training in a longer view. All elements are important and build upon one another. You don't just do one over and over. The body adjusts and you don't get results. What works great in Feb will not be helping much in March. You have to switch it up.