I really like "Image In The Sand" and "Shadows And Symbols" (the openers to S7), as they show who each of the characters are with their own storylines, introduce Ezri to the universe, show the friendships and bonds that exist, where they're at with the war, without really needing to know that much about the series to begin with.
Commander Austin Harris, First Officer, Deep Space Nine (by FltCpt. Bossco)
8.01 - Darkest Before Dawn
(Chapter 8 added, 12/09/2015)