Wow! I've got to get back into the forums more! Nice to think I spawned this discussion!
As to my top three, I go straight to TFTO. Having bought it as vinyl, the double spread, and inside cover make a memorable package, to say nothing of the music!! Cheers KeithieW!!
Number two is probably Olias. Again, a testament to what a loss the 12" album cover was...
The cover's intricate artwork was also set on embossed board.
Three is tough... I was a big Roger Dean fan (I have a mint condition copy of "Views"!) but I'll "spread my love" to another artistic realm... Perhaps ANY photo cover of Kate Bush! I'll stick to "classics" and go with Nursery Cryme. The "style" and that doll on skates kinda haunts me...