As mentioned over in this answer, they're not regarded higher or lower than the others, since they are all the word of God. Everyone's individual experience will vary with which scriptures are emphasized. Usually, the Book of Mormon and Bible are read from most often.
The Doctrine & Covenants are mentioned for a more recent, historical account of God's revelations and on matters of things that are not clearly covered already in ancient scripture. The Pearl of Great Price is probably least often cited, but contains important clarifications and expansion of some of the events in Genesis, Joseph Smith's personal history, and a better account of Matthew 23-24. Not because it's least important, but because it's the smallest book.
The Book of Mormon is probably the most practical to apply in one's life since it is the only canonized book of LDS scripture which was written not only as a historial record like the others, but the authors of the Book of Mormon indicate they saw our day and wrote their record for us in our time.