OK, here I go...
My favourite Opeth album is:
1. Still Life
Followed by:
2. Morningrise
3. My Arms, Your Hearse
4. Damnation
5. Blackwater Park
6. Orchid
7. Deliverance
Now. Personally, I thought Damnation was an improvement from it's predecessor and companion (Deliverance). It is the more unique chapter of Opeth's career and shows their willingness to explore. Rather than contrasting heavy and light they specifically focused on their delicate side (whether or not any Damnation track lives up to past delicates as Face of Melinda or To Bid You Farewell). I like this uniform approach, it steps beyond their previous outings and more astoundingly outside of the boundaries of heavy metal entirely (since it can't even be termed as a heavy metal album). I also believe it allows Mikael Akerfeldt to shine vocally (perhaps more so than ever before, though I do enjoy the mix of violent, deathly roars and clean mellow, melancholy sung vocals). I did miss the powerful guitar riffs with the occassional gut wrenching solo. But overall I must say Damnation is beautifully assembled, well executed, and certainly on par with Opeth's previous releases.
Just my $0.02.