I don't count any of the aforementioned songs among my favourites, anyway. Well, perhaps Theme of Simon. But! Some utter darlings:
Forest of Monsters, out of many, many sublime pieces from Super Castlevania IV. There's a strong air of meditative mystery to it, as well as a distinct sense of melancholy. A very good, active bassline offers contrast and structure to the ponderous atmosphere. I love it for its subtlety and understatedness, without falling into the mundane.
Dance of Gold, from Symphony of the Night. The grandeur of this track is palpable. It's not an empty, vacuous sort of majesty either, but a supremely confident display of sweeping motifs; the highs and the lows. The composition is allowed to breathe, and it's not chained down by a mandated action backbeat like some later Yamane tracks. It is the classiest.
Praying Hands, from Belmont's Revenge. The progressive, unfolding nature of the song is spellbinding. To be able to command such an expansive array of emotions with such limited tools speaks of some kind of genius. The intro alone has more compositional merit than the series has witnessed in years.
Moon Fight, from Castlevania Chronicles. The track and related soundtrack were already good, but Fujimori made them shine, bless his synth-humping soul. The instrumentation, then, is the main event here, with the tremendous slap bass stealing the spotlight quite effortlessly. It wasn't lost on the author either, as it's granted a fantastic solo moment towards the end of the song.
Old Enemy, from Harmony of Dissonance. The percussion is absolutely bonkers. It retains at the very least the initial breakneck pace throughout, but just as you think you've become accustomed to it, there's a sudden rise in the intensity of the rolls. It's genuinely alarming if it catches you off-guard, and kind of too good for the boss fight it accompanies.
Aria of Nightmare. Lament of Innocence always struck me as an introspective, rather solitary experience. The nocturnal setting amidst the woods has something to do with it, I guess. Anyway, since that is the prevailing mood I associate it with in my mind, I tend to treasure the songs that reflect that particular atmosphere. Aria is incredibly effective as an exercise in spooky minimalistic ambience, and refreshing amongst the (similarly good) lavish melodies of its compatriots.
Those are kind of in a descending order. At least, listed in the sequence I thought of them. Of course, I thought of more still, but, well.