I've played so many castlevanias 2D, 3D, handhelds, consoles, even mercury steam's trilogy (Didn't play like a castlevania games), it's one of my all time favourites franchises so I can really tell you that it has an atmosphere of it's own, with good enough and enjoyable game play, with great music to accompany that

90% atmosphere
10% great sprites

Wasn't that 3D? Castlvania is 2D. Anything else is just Castlevania by name. 

Because they are so good. My personal favourites are Circle of the Moon and Order of Ecclesia.

To the OP, we cant talk Castlevania if you havent beaten or tried at least, SotN. It was a classic series for me, ever since NES times. But I didnt like it that much until I got SotN. I played it until PS3, because I didnt have interest in it when I had PSX. After that, I have it in PS3, PSP, PSVita, PC (yes, emulated), and even on my cellphone, for when I have to wait too long in the bus for example. It has became kind of my way to escape reality whenever im bored to death.
It has even forced me to get all the others that I can get my hands on. I already got from Ebay, Castlevania Lamment of Innocence and Curse of Darkness, and got all of the PSN store that are available. Some of them are just crap (for me) but Im going to beat them all (at some point) in honor to SotN.

SotN is really good. I love it to death with Crissaegrim in my hand, but Castlevania was more than that game alone. The NES games, the PC Engine game, the SNES and MegaDrive games were all of the highest quality you could get at the time. It was also somewhat the dark souls of it's time, with the artstyle and atmostphere and high difficulty. That said, Super Castlevania IV is still in my opinion one of the best traditional Castlevania's ever made.

SoTN is so vastly overrated. I hate what that game did to the series. Fuck that game! Castlevania in 8 and 16-bit era are the best. Gothic and very horror focused rather than glam rock RPG Metroid games. I like Metroid but not in my Castlevania. Ok, I like some post-Sotn CVs but none come close to the greatness of SCV4. Linear action horror as it should be. Lords of Shadow 1 was great as it went back to the gothic western inspired horror. Not anime. (I like anime just not for CV in general) I fell out of love with CV games in general once Sotn release. God I hate that game. I do like the music but not the game.

The controls are responsive and can be mastered quite easily. The character may be slow, but the control is precise. The games are generally good to amazing. The soundtracks, art design, level design and challenge is usually top notch. The theme is cool too.

Personally, I don't like any of the 8 and 16 bit games.

All the metroidvania games though are great. I'm completed SotN, GBA games, and DS games multiple times.

It's all because of Symphony of the Night. The other games were all forgettable and/or bad.