Essential Trip-hop Albums

I've been listening to trip-hop since I heard Portishead's Wandering Stars playing after a video stream of a Microsoft conference. That was about four years ago and since then I've only purchased Portishead's Dummy album. I have downloaded songs from several artists, but I've only one album after four years. For some reason I never got around to buying Portishead's second album. Songs like "Cowboy" didn't really catch me, though "Western Eyes" was pretty good. I'm going to buy Daughter Darling's Sweet Shadows soon, I loved Broken Bridge and Mermaid. What other albums are quintessential to a trip-hop fan's collection? How is Bows? I downloaded "King Deluxe"(thanks to novadrops :D) and it's AWESOME to say the least. Really reminds me of Portishead's best for some reason.

Other bands I like:

Lamb
Massive Attack
Air
Mono
Hooverphonic
Canidas
Sneaker Pimps

Which albums from these bands?