Ark, you like Lords of Shadow, and think that the NES Castlevanias haven't aged well.
This is the start of a very bad relationship.
Seriously though, as someone who's played and beaten every CV in the series, I can name something from each one that could've been better. LoS, however, is the only Castlevania game I can say I truly disliked. They slaughtered the mythos and turned it into a hackneyed Lord of the Rings/Bram Stoker's Dracula tribute. It's just so blatantly a ham-fisted shot at marketing towards a western audience. I could go on for ages, but I'd rather praise CV than hate on it. I will say that I still have a hard time even acknowledging LoS as Castlevania game, since if it wasn't titled so, I'd never guess it was a Castlevanie game.
The original three have aged extremely well (though II is arguable), primarily because they were, contrary to most modern games, well-designed. They were difficult as hell, but what makes me appreciate them is that every time I die in one of them, I can't help but laugh at the ingenious avenues they took to subvert the player--I know that when I die, it was because I messed up and fell into a deliberate trap.
The hallmark of the entire series has been its aggregation as what Richard Wagner called the "gesamtkunstwerk," or "complete art work." The music, the design, the story, which despite being convoluted to the point of not making any sense, was just plain ****ing cool and imaginative; everything. Obviously though, when Michiru Yamane came on board, the baroque stylism of the series was really illustrated along with Ayami Kojima's stuff.
I'll stop there, but yeah, I'm a pretty big CV fanboy. I can't help it though, with how terrific a series it is from just about every angle. In closing, my favorites are probably Dracula's Curse, IV, Rondo, SotN and CoD, each for similar as well as different reasons.