My favoriete album is Origin because I just love the dark atmosphere of it. The songs were catchy yet mournful and creepy (Where Will u Go, Lies, Even in Death), and there was an almost "romanticized" feeling in some of the tracks which I found hauntingly beautiful. And Eternal just happens to be my favoriete instrumental - I love the piano and the thunderstorm in the background was soothing.
It's really hard to pick. Every album is special in its own way to me. It's just like picking a favoriete among a collection of amazing tracks. So, every album is my favorite. :Q