Alright, I'll give this a shot. Like everyone before me has said, this was a very hard list to pick. There are so many bands I absolutely love that just don't have that one standout album that you'd really go for. Likewise, there are some albums with terrific songs on them that might not burn at that supernova intensity the entire way though.
In any case, leave me one a deserted island with these five discs and I'll die happy.
I have a bit more of a pop music bent that some of the lists that have gone before.
(In no particular order).
Fleetwood Mac - Rumours [1977] - The best pop album ever? Brilliant songwriting/musicianship/production the entire way through.
Rolling Stones - Exile on Main St. [1972] - The best rock album ever? IMO this is the best album to come out of the 'Stones brilliant period with Mic Taylor. Love it. Not a bad track on the album.
Miles Davis and Gil Evans - Porgy and Bess [1959] - An irrational choice perhaps, but this is my all time favorite jazz album. Maybe its because it has Davis and Evans reinterpreting Gershwin? Its a brilliant album that, like all the albums on this list, moves me every time I hear it.
Paul Simon - Graceland [1986] - As a songwriter, Simon has incredible honesty and vulnerability that really give his songs beauty. Mix that with some incredibly talented African musicians and some amazing studio production work and you have magic.
And, last, but not least, Stevie Wonder - Songs in the Key of Life [1976] - Stevie's voice is a gift from up above. Its a very tough call between this album and Inversions but I ultimately chose this one. IMO this is his magnum opus.