So, I'm gonna be the odd one out here, since I actually did get into Opeth via Blackwater Park, 'The Drapery Falls' is my favourite Opeth song, I like the last three records, and I don't own Morningrise (I actually did buy it a few years ago, but then I went to the pub, got drunk, accidentally left it behind and never saw it again).
Nevertheless though, Orchid is probably the Opeth album I listen to the most, the dual guitar-centric writing on that album knocks me out. Every now and again I try to learn how to play songs from that album, but usually give up after half an hour of forgetting which guitar line I'm actually following.