Legends, Order of Shadows, Lords of Shadow, and Mirror of Fate.
Legends because it's way too easy. For example, being able to use invincibility during boss fights breaks the game in my opinion. Oh, and the levels are too long and boring. Adventure and Belmont's Revenge are better than Legends and I actually enjoyed both of them.
OoS because it's pretty bad, lol. But then again, what can you expect from a 6 year old cell phone game?
Lords of Shadow and Mirror of Fate for many reasons. I'm not saying the music is bad, but I just dislike style of music they chose for the LoS series, it just doesn't sound Castlevania like in my opinion. I'm also not a huge fan of the LoS/MoF story either, which makes a game hard to play if I don't like the story. The gameplay is alright in both games. I don't really have any complaints against the gameplay.
The Titan fights in LoS were also things that I disliked, but that's more of a minor gripe. Mirror of Fate was better than LoS in my opinion. I liked the gameplay better in MoF than LoS, but...with both games, it just feels like something is missing for me. MoF, while better than LoS, still wasn't a game I really cared for much. It just feels like that "Castlevania charm" is missing in both LoS and MoF. As standalone games, LoS and MoF are "okay" games, even though I'm not a fan of them. As Castlevania games, they just don't feel right to me. This is coming from someone who has played every Castlevania game except The Arcade and the Pachislot games, and have liked them all except the four games I've listed here.
On a side note, the only one I didn't hate, but didn't like either was Harmony of Despair. I was more neutral on it than anything.