Slip It In (1984) - my introduction to Black Flag - not sure if I liked it, but few other musics intrigued me like it did - and then I fell in love.
In My Head (1985) - the album I grab most often these days, but then these other three usually follow.
The Process of Weeding Out (1985) - probably my favorite Black Flag recording overall - only bothered with it because of how much I liked the live versions from Live \'84 as it changed my idea of Black Flag being without vocals.
Live \'84 - bought it because I wanted to hear Slip It In live and because it was either $2 or 4$ - it just made me want to hear more of the twisted jazz/prog/heavy guitar from Ginn.
Nervous Breakdown EP (1978) - because I love Morris\' vocals.
Jealous Again EP (1980) - because the songs are brilliant.