My kids are in Catholic school so here's what I hear on the ones you mention:
Mercy - can also be hard to get into because of lots of alums, very affluent parish, strong high school outplacement, I like their uniforms!
Little Flower - nice campus, great field, strongest clergy presence of all the schools, solid traditional instruction
Our Lady of Lourdes - more diverse than other Bethesda schools, more of a "city feel" to it's campus, one of the few with a 3 yo nursery program
St. Ann's - never hear much about them
St. Raphael's - newest school in area, only goes through grade 2-3 currently, spinoff from St. Elizabeth's
Holy Cross, Holy Redeemer, - don't know them
Our Lady of Victory - smaller than I thought, strong reputation,
Others areound are Holy Trinity (hard to get in and more expensive than others) and Annunciation (very small classes because of low enrollment)