Out of all the games in the series, CV4 is by far the one I dislike the most; it is too long and plodding (as I've said other places, there is a level subsection where you spend half a minute just hanging by the whip while the room spins around you), the spritework is pretty inconsistent, the bosses are almost all cheap assholes who don't take strategy to beat but just a rapid-fire controller, and the music is very hit-or-miss and a lot of the better music is marred by terrible samples, especially the one for the piano. Dracula X for SNES is still cheap and grindy but the art and music are obviously much better overall.
Similarly, Dawn of Sorrow was much more fun than Aria of Sorrow, which was too easy (and too grindy) for me to enjoy, though I find it frustrating that both required soul-grinding in order to get the good ending. At least Dawn's necessary souls were pretty common and easy to find. Whatever better story AoS might have had over DoS flew right past me in the face of a pretty poor localization and very little dialogue in the first place. The one thing I'll give it is that the touchscreen stuff in DoS was pretty mediocre.
Ecclesia had pretty terrible music up until the battle with Albus; while a few of the songs up until that point are decent, most of them are pretty dull and some of them are just dissonant and directionless. Which makes the fact the rest of the game has actually really good music all the more striking, granted, but only serves to grind down my patience at what's basically the first half of the game.