I heard that this year without GRE scores for many programs, the decisions relied heavily on personal statements and letters of recommendation. The following advice came from various faculty on admissions committees in a webinar I attended last year. To have the best possible personal statement you should have several people read it (especially people who have been involved in admissions decisions) and give feedback with many drafts before the final version. Letters of rec should be from someone who you are sure can write you a STRONG recommendation and someone you actually closely worked with that can give details about why they think you are an excellent candidate is WAY better than a big name who will write vaguely about you. Letters of rec should still preferably be written by PhDs. Hope that helps and good luck!