Grunge isn't really a genre and Alice In Chains don't really sound much like the bands labeled "grunge". They sound more like sludge metal to me if anything.
Grunge isn't a genre? How so? There are many many grunge acts other than the big 4. Thrash started out with just a big 4. Granted the genre is dead now but it's impact cannot be underestimated.
I vote for Dirt because it's a fantastically-written album and the only one I've heard. For some reason, I never felt compelled to explore their discography.