I know AskGamblersProfile isn’t made for manga fans, but I use it to log my One Piece episode reactions. The interface is clean and lets me save personal notes on arcs and OP/ED songs. It’s missing a proper series list though, which gets annoying. askgamblersprofile I’ve gotten a few fellow anime lovers to try it too. Not perfect, but I appreciate having all my thoughts in one spot. Wish they’d add genre tags next update.