That is the beauty of the Castlevania franchise, it has lasted so long that there are fans of certain releases, or the whole franchise itself. I am partial to Simon's Quest myself but have enjoyed playing Rondo of Blood on that Castlevania release for PSP (Symphony of the Night is another I enjoy - pretty much anything without those darn flying Madusa heads 😂).
The homebrew community are certainly kicking up dust and showing off their skills. I hope some of these companies see that and try to hire some of these developers. Passion cannot be taught.
I couldn't really choose any subseries in particular as my favourite, but there is something to be said about the overall visual presentation before Iga became the patron of the series. It's just timeless.
The older pixel limited entries hold a certain charm about them. Newer stuff looks great but those 8 and 16-Bit releases are simplay fantastic looking. I know it is probably nostalgia speaking but to me, they stand out as more visually appealing versus stuff on the GBA and DS stuff.