As those above me said, the two of them are great together, but the best way to really learn Japanese is on two fronts: ātop-downā and ābottom-up.ā
The bottom-up front is what WaniKani and Bunpro are for. Iād also recommend japanese.io and/or Anki for making flashcards out of the many, many words that WaniKani doesnāt have. I personally add flashcards for words that I encounter if Iāve hit Guru in the kanji. That way, it feels like Iām just expanding WaniKani.
The top-down front is where you learn Japanese by actually using it the way you want to someday: listening; speaking; reading; writing. I strongly recommend you start listening to content intended for native speakers, like NHK or Japanese YouTube videos or untranslated anime or video games. You wonāt understand a thing at first (and youāll probably feel frustrated for a while), but this is the part that actually gets you to fluency.
The real gains come in how these two tracks cross-pollinate. Youāll start to hear a word from WaniKani or a grammar point from Bunpro. Even if itās only once or twice, that will greatly boost your memory of those items.
But keep trying new things and working in more study techniques that work for you. Youāll surprise yourself with your gains!