wow, how Pink Floyd's music has influenced my life in the last 5 years(yes, i'm only 22) a lot has derived for me from their music......but back to the topic, i have actually gone through every single album listed, plus all their solos....for those who dont know, there are some good songs hidden in those solo albums.
its hard to break it down past 5, but i'll put in down to 2....DSOTM and The Wall.
I gave my vote to The WALL for a few reasons: the movie with it was quite an emotional ride, there is a lot of messages in that movie. It is a Double CD, The CD's had Another Brick In The Wall, Hey You(man this one gets your mind rollin) and Comfortably Numb.
If The Wall were only 1 cd i would give my vote to DSOTM, the correlation with the wizard of oz was cool, it's awesome how the cd runs through from beginning to end(from birth to death) and the songs run together and the hype in general.