First of all I'd to say that, as an amateur gamer, Castlevania was and is one of the best childhood games I've ever played along with other classic games like Mortal Kombat or Kid Chameleon from Sega Genesis.
Personally, my favourite Castlevania games are Bloodlines from Sega Genesis, which was the first CV game where I started. And much later on, the two PS2 3d Castlevanias: Lament of Innocence and Curse of Darkness. Those two are definitly the BEST on my opinion, I mean those two are decent, classics, addictive because of the different mods or optional bosses. Without doubts some of the best games of the franchise, of course, next to Symphony of the Night. In fact, If I had to do a raiting or Top 10 about these games, here's my rate:
1-Symphony of the Night
2-Lament of Innocence
3-Curse of Darkness
I'm also of those who think the Lords of Shadow reboot destroyed the franchise for many reasons. Pretty much I prefer LoI events about Dracula's origin as Mathias Cronqvist over LoS reboot about Dracula's born as a member of the Belmont Clan that became "corrupted" and somewhat turned into an anti-hero like version of Dracula. The only interesting and mysterious character for me it was Zobek.
The music also, you know, I'm not gonna say it sucks or lower the work of Oscar Araujo like a jackass, because everyone has their own style of music, but I don't really like it, hardly I can remember or prefer at least one of the characters own theme and honestly felt I wasn't played a Castlevania game. The wonderful work from Michuri Yamane, on the other hand, was just a masterpiece, if I remember correctly she worked on a couple of Castlevania games OST but I particulary heard most of his fantastic work on Lament of Innocence and Curse of Darkness and man...I highly recommend hear the OST from those two, it is fantastic, suitable on every Stage atmosphere and many of those differ from each other.