Epilouge is a gorgeous song, and I think they have so many beautiful parts that are connected to brutal moments of beauty to. I also think "By the Pain I See In Others" is a beautiful track, yet it's so brutal and morbid.
Patterns in the Ivy I and II
Black Rose Immortal
Still Day
The Moor
Benighted
Face of Melinda
TBYF
Credence
When
Epilogue
Hope Leaves
Weakness
Deliverance
Opeth songs tend to always give off a strong sense of pure beauty. Although, if I had to choose only one, then I would most deffinately choose ''To Bid You Farewell''.