Yeah, it's still unmatched 26 years later. I think the closest Castlevania soundtrack in terms of quality is Lament of Innocence, but SotN is clearly superior.
There are some great game soundtrack out there, but nothing as consistently good as Castlevania. Gradius Gaiden comes close to SotN but is still not brilliant enough to top it. Shadow of the Colossus is top-notch. Final Fantasy has some really well done soundtracks. Okami is pretty great, although five discs of Japanese folk music gets old quickly. Silent Hill 2 has awesome music, but too much of the OST is awful cacaphonic noise that I can't get behind. Timespinner is great - good enough that I bought the physical soundtrack, and that doesn't happen much these days. Those are the only really notable soundtracks to come to mind.