Castle corridor (AoS) and Abandoned Castle (CoD) are really good. But, the most special for me, is Dracula´s Castle from SoTN. I remember the first time I played it, and after a few moments of almost silence, with the thunder and killed wargs sounds and screams, listening to Dracula´s Castle simply was amazing for me. The same would be to SCIV´s Theme of Simon...
...oh, and I also like SNES Bloodlines
... Too difficult to decide wich one
.