Tips on applying to Deferred MBA programs

My S is a college senior and is just getting started with the process of applying to deferred MBA programs. He’ll be taking some practice GRE and GMAT tests this week to determine which would be a better test for him. For letters of recommendation, I’m guessing he will ask one professor and one person from his internship. For the professional letter, does it seem better to ask a leader from the team he worked on who has more direct experience with his work, or someone more senior in the company (a partner who has been involved in mentoring him)?

Any tips on writing the personal statement? Any other thoughts about what helped you or your child with admissions to a deferred MBA program. Thanks for any help!