My 最喜爱的 album is Origin because I just 爱情 the dark atmosphere of it. The songs were catchy yet mournful and creepy (Where Will 你 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 最喜爱的 instrumental - I 爱情 the 钢琴 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 最喜爱的 among a collection of amazing tracks. So, every album is my favorite. :Q