Well, the poll results are validation! It seems to confirm that Kill 'em All isn't an undisputed top 3 album in the way the article that inspired the question suggested.
I'm kinda surprised that Ride the Lightning is up there, but the rest is roughly as I thought it'd go.
Personally, I think I'd put in Death Magnetic in the top 3, just because it was the last album of theirs I really enjoyed listening to and I'd probably actually enjoy it a little more than some of the others that are deemed classics of the genre but feel much more well worn to me.
Elsewhere, I'd juggle Black, AJFA and MOP. I'm not sure which would come out on top on any given day - all of them have some classics - MOP has... ...MOP and Orion, Black has Kirk's best solo work (imo) in The Unforgiven, My Friend Of Misery, maybe The Struggle Within, and AJFA has One, Blackened, Dyers Eve.
Each also some 'could happily never listen to them again' tracks (I'm particularly looking at you, Of Wolf and Man -

), I don't think Metallica have an album with "no skips" for me but I reckon some parts of their catalogue easily hits differently with different people.
Who voted St Anger?!
I just ordered a couple of tickets for Metallica next summer, so I'll probably have to familiarise myself with the latest album before then.