This is a tough one for me. While I think Sergent Peppers Lonely Hearts Club Band and Dark Side of the Moon are arguabley the most important Albums of all time, I have to go with one of three that personally have changed my life in the way that I listen to and appreciate music.
And that winner is:

1- Dancing on a Volcano
2- Entangled
3- Squonk
4- Mad Man Moom
5- Robbery Assult and Battery
6- Ripples
7- A Trick of the Tail
8- Los Endos
The other two albums are:
V, by Spock's Beard and Head, by the Monkees