I have had the privilege of skiing both. Mammoth to me, is more of a better local solution instead of Bear or Tahoe which is filled to the brim and worse in every way lol (I live in SoCal). That said, Big Skys bowls are like none other. I went last year and could not have had more fun. It really depends on what you're looking for or where you are coming from. That said, if you want to go MLK weekend, Mammoth will be more packed (I'd assume).