1) Should I choose a recommender who knows me best but does not have a "fancy" title or a recommender who knows me a bit less but who has a "fancier" title (say, a young manager vs. a partner)?

2) Does not having a recommendation from your current direct supervisor somehow harm your application at top schools? Stanford and Columbia explicitly ask recommendations from your direct current supervisor. They say they will understand if you are not able to provide such recommendations, but doesn't it affect your application?

Thanks a lot.