All Killer, No Filler.

OK, you musical heathens, the maxim here is Know Your Heritage.
Let's see if we can manage some adult debate (ask a parent if you're unsure :D) on whether my choices for 10 must-haves should be listed above other classic albums.

In no particular order, the best 5 with some highlight tracks...

Pink Floyd - Wish You Were Here
Although I could quite easily have four Floyd albums in my list, I'm restricting myself to just this one. Many may prefer Dark Side but there's just a little too much wailing for me! Animals isn't as strong, and The Wall too depressing, but this is pure quality all the way.
Welcome To The Machine - in retrospect, almost seems written about Johnathan King :-/
Have A Cigar - a spot-on snipe at the music industry of the time (has it changed?)
Shine On You Crazy Diamond - the epic homage.
There is not even a merely decent track on the album because they're all outstanding. I remember listening to it for the first time and just being blown away by the mastery; I sat entranced for three quarters of an hour just listening to it, then did it again.
This is the prog rock yardstick that all others have to be measured by.

Fleetwood Mac - Rumours
Although Fleetwood Mac had been popular for a long time, Rumours really was a huge step up from previoius albums. Made at a time when the group was riding rough seas as a unit, many tracks seem written by member about other member. Every track is a perfectly cut and polished jewel.
The Chain - with the most famous bassline in the UK during the 70s & 80s, this is one of the 'sniper' songs.
Don't Stop - pure pop, perfectly performed. :)

Prince - Sign 'O' The Times
"What? Prince??" I hear across the ether. Yes, Prince, and not just because it's him. I do like most of Prince's stuff but SOTT stands head and shoulders above everything else he's done (that I've heard). He plays pop, rock, blues, jazz and a little more pop over this double album and manages to finish without having fired a dud. If this album has a downside, it's the slightly flat production, but that doesn't detract from it as a whole.
The Cross - superb uplifting lyrics over a relentless rock backing that shouldn't really go together yet complement each other perfectly.
Sign 'O' The Times - as the title suggest, a thoughtful and cynical look at the way things were.
If I Was Your Girlfriend - darkly menacing track with slightly speeded up vocals that is almost unnerving and very catchy at the same time.
The Ballad Of Dorothy Parker - jazzy and brilliantly wacky.

Michael Jackson - Thriller
This isn't here because everyone says it's great, it's here because it is great. Rod Temperton came up trumps for MJ again, after penning Off The Wall and Rock With You for his previous album, also produced by Quincy Jones. Is there a weak track? Possibly PYT (Pretty Young Thing), but it's still perfect disco of the age.
Thriller - what can you say? It wasn't the video that made this song great, although the troupe dancing still leaves me in awe, it was already the most popular track in discos, on the radio and at parties.
Beat It - who'd have thought of stabbing a rock guitar solo through a disco song, eh? Doing so changed the music world and disco music died of blood loss.
Billie Jean - the second track released and a worldwide smash for good reason. Velvet vocals and a pulsing rhythm made it impossible to not dance to.

Metallica - Metallica
AKA The Black Album. Although they were not exactly unknown, this album broke Metallica worldwide on a huge scale. Many fans said they'd sold out their thrash roots, when all they'd really done was evolve. The production is as awsome as the music. Playing this cassette in the car too much may well have influenced by kids away from that eurotrance stuff (Scoooooteeeeer, STFU!) but I can live with that :).
The Unforgiven - by previous standards, almost a lush love song!
Enter Sandman - there's only one way to listen to this epic rock track, LOUD. Superb.

OK, that's 5, but honourable mentions have to go to the next 5; you can be forgiven for not having these...

Def Leppard - Hysteria
Their drummer only has one arm, you know. ;) The producer is married to Shania Twain, you know. ;) ;)

Bob Marley - Legend
Isn't it daft to put a 'greatest hits' album in a list like this? Not when it's biggest selling and finest reggae album you'll find.

Dire Straits - Brothers In Arms
Superb but for one song that's only great, this would easily be in the other half if Walk Of Life wasn't on it and Private Investigations was.

Meat Loaf - Bat Out Of Hell
The first one. As great as this album is (which is incredibly great), it's just not quite there... perhaps it's the production, perhaps it's Steinman's songs... probably it's Steinman himself. Don't let this deter you from getting the third most fine rock album of all time, though.

Nirvana - Nevermind
'nuff said.