In Excelsis - Ladder of Lust
http://www.discogs.com/image/R-475961-1138387647.jpeg
I've never thought about album art in terms of favorites, but it's certainly up there if I had to choose.
Also, how many people here know that the cover to Unknown Pleasures is radar traces from a Pulsar (i.e. a dead star). If you ever get a chance to listen to these transmissions, they sound like a series of tonal droning, like you'd experience with something like Tennitus. If you think about this, and Ian's later suicide, the lyrics to "Transmission" take on new meaning:
Radio, live transmission.
Radio, live transmission.
Listen to the silence, let it ring on.
Eyes, dark grey lenses frightened of the sun.
We would have a fine time living in the night,
Left to blind destruction,
Waiting for our sight.
And we would go on as though nothing was wrong.
And hide from these days we remained all alone.
Staying in the same place, just staying out the time.
Touching from a distance,
Further all the time.
Dance, dance, dance, dance, dance, to the radio. (x4)
Well I could call out when the going gets tough.
The things that we've learnt are no longer enough.
No language, just sound, that's all we need know, to synchronise
love to the beat of the show.
And we could dance.
Dance, dance, dance, dance, dance, to the radio. (x4)
Favourite Album Art.
FOR THE WIN I'm saying Only Theatre of Pain by Christian Death. Just the striking, dark, haunting imagery drawn in a wonderous strange ink. The birth of American Goth rock and Romanticized Deathrock in my opinion. 
