Lots of great advice above.
There is resume fodder (check the box) and then there are the real things (meaningful). What you do with the role will determine which one it is. If you do nothing as a Class Officer it is just as meaningful as doing nothing at anything else.
Unfortunately, as with any selection process, there is a bit of game the candidates play to optimize or 'max' their score. Its normal, and the selection board no doubt has so much experience with it that they have a reasonably good detector. Accumulating bullet points for your resume only goes so far. None suggests you didn't do enough. Too many and you probably are not doing much in each one so why do I care?
I'll be honest, what I suggested to my DS was if there are easy, low effort adds for your resume, then get them, but realize its just filler. The things that truly matter are the activities that you put yourself into 100%. These activities show who you are and you can have real conversations about them.
My DS earned his Private Pilot License in High School. I don't think the checkbox next to PPL got him in. I think the jobs he worked to pay for it, the time he spent doing it, the sacrifices he made to study and prepare for flights, and the long term goal/commitment that it demonstrated is what was meaningful.
The fact that he was doing it because he loved flying instead of just to build his resume was also important to me. Don't do things just to pad the resume unless they do not take much time - like NHS - he was getting good grades anyway so why not add NHS? But, ideally, you find a couple things that you are truly interested in. Activities you really want to explore. Put yourself into them and if you develop a passion for them, you will have an interesting and meaningful experience where you learn important lessons about people, about life and about yourself. I know anyone reading this is likely heart set on USAFA. The fact is that you are young and have so much life ahead of you. Figuring out your passions is much more important than padding a resume for a school that you may or may not get accepted to, a school you may or may not change your mind about. Pursue activities that interest you, excite you and that will help you gain experiences. In the beginning, you might just be eliminating things as you discover, you don't love them. But persevere and hopefully you will find a couple things that you can't wait to spend more time doing. If you can do this, you will become a better candidate, but also, more importantly, a better you.
My bet is that Class and NHS Officer positions are scrutinized for value. They are so variable from school to school that they don't earn you much just by having the checkbox. if you have to pick, pick the one that does more and/or with the better faculty advisor.
