I must say, there certainly is a diversity of opinions in this thread. Outspoken love, caustic hate, and for all kinds of different titles (including directly comparing a ClassicVania to a MetroidVania). Guess it goes to show that there's some variety and that there's a lot of different things to love in this series.

Personally, I haven't played every single Castlevania, and the only one I have REALLY disliked at all is Castlevania Legends. Sonia Belmont has a nice 90s anime look to her design, but her game just isn't any fun, it's a real drag. I don't love Simon's Quest, but it still has some very nice graphics and music to it, along with at least some good conceptual ideas, even if the execution is lukewarm, so I like it more than Legends.

>Symphony Of The Night
>Circle Of The Moon
>Harmony Of Dissonance
>Aria Of Sorrow
>Dawn Of Sorrow
>Order Of Ecclesia
I have played all of these MetroidVanias/IGAvanias, and I like all of them. Some more than others, and there's various ways I can compare them in what they do better than each other, though I never feel that these can be compared closely to the ClassicVanias due to how different they play.

Of the ClassicVanias, I could flip a coin between Super Castlevania and Dracula X for my favorites, which probably isn't a popular opinion, but I've also yet to play Rondo Of Blood, or Dracula's Curse.