I’m also at Level 3 and asking the exact same question right now!!
My goal is slightly different from yours.
I’m trying to get “real world” able to speak and converse and read passably fluently because I will be going to Japan soon.
From what I've seen...
I’ve been doing Duolingo (in conjunction with Google Translate) for over a year. While DL didn’t “officially” teach grammar or speaking skills, I have been absorbing that AND all of the kanji that was presented in the first 3 levels of WK, and apparently a lot of it through level 40 (over 1200 words I learned in DL in a year and I’m not even halfway through the tree). I use DL as flashcards. Whenever a word comes up, I go through the pronunciation and meaning. If I miss writing any little part of the kanji into Google translate in handwriting mode, then I miss the question on purpose so that it comes up again in the same session until I get it exactly perfect (same with the grammar).
I found Wanikani helpful as like “flashcards” for learning the kanji. On the boards here, I see people with really high WK levels (20-plus) struggling with translating and speaking and listening skills. Even though every flash card has two voice tracks to hear each kanji promotion. I believe that Duolingo is superior in quizzing you on vocabulary in context (complete in a sentence with grammar and hearing it spoken or having to speak it [simply use keyboard input with microphone]) while you HEAR it being said. I will admit within WK levels 1-3; there were only maybe 15-20 (essentially what I’ve been calling “compound kanji” sharing a primary kanji that I already had learned) that I hadn’t already learned in Duolingo. But just as if I’d learned it in a college class, I tend to agree with WaniKani policy that “it didn’t hurt to drill on it, even if you ‘already knowit’”.
But the way WK does SRS and sort of “Force feeds you” the reviews, YOU WILL LEARN! I believe that in combination with Tofugu or Take Kim’s or college coursework/textbook you can make up the “grammar deficit”. Also, IF YOU CAN SPEND THE TIME while doing WK reviews to scroll down each time and really learn the type of word and the nicely selected SAMPLE SENTENCES, you can see the kanji “in context” and soak in how it’s used. (I think DuoLingo is superior in this aspect, in that you can hit the button and HEAR the entire sentence in context and check if you had the correct "reading “in your mind”; Duolingo is 90% sample sentences, drilling input and output). (Nb. several people on this forum gave high reviews to LingoDeer for grammar learning). (Pretty much ALL over this forum, I’ve only seen them saying Duolingo is useless; apparently I use it differently than they do, plus there was a new tree two months ago)
I haven’t really used Anki decks for learning kanji. I found them too slow to load, too picky about the answers; Ididn’t experiment with the repetition available there (apparently, it’s tunable). I prefer to let WaniKani track all of that and feed me reviews, and use their great “notes”. For the record… If WaniKani didn’t have a NOTES FIELD for my own personal ways of remembering things, I would not use WK at all–but they do!!
In my case, personally, I conclude...
So… Should I reward these WaniKani creators with $300 for a “lifetime membership”? (For me, I expect that it would take 2 years at $10/month, so $240; plus reviews thereafter because if you don’t use it, you really do lose it)…I think it’s a bit of a windfall to them for a “glorified Anki deck”, but I have decided that it’s worth it (because they did a better job with it than I could and I’m lazy, and I’ll want to refer to it periodically over the next decade; and it has more information than an Anki deck).
BUT right now it’s taking away from my Duolingo progress, so I will focus on that right now until I am finished with “the tree” and then drop some coin here. I’m only part way through my Japanese learning journey.
FORUM RAVE:
I am LOVING the book clubs here, and even seen a few that are reading out loud, “live”, which I think is an amazing “next step” for reading, speaking AND listening skills. And the people here are OUTSTANDING! Can’t praise highly enough (helpful, creative and FUN)
What *may* be best for CANS
I suspect that “reading aloud” and “manga translation” activities like those together with WaniKani (to learn reading and vocab fastest) may bring YOU closest to your goal fastest, CANS. The goal of enjoying anime with Japanese subtitles (input). Although that involves listening AND reading, it seems to me that Wanikani might be good for you for getting fast at kanji recognition for meaning on the fly as those subtitles zoom by (reading) and if you keep trying as you can more and more kanji, it will essentially be LIKE immersion (but into a subject matter that’s FUN for you). And… If you practice translating the relevant manga sentence by sentence while studying relevant grammar on the internet (there might be a good book club here in the forum for you, like JoJo’s Bizarre Adventure reading club), you would build up the vocabulary used in that anime/manga even faster, thus keep advancing while enjoying.
Thanks to both WK itself, which taught me how to actually read these squiggles out loud (not just their meanings), and to the helpful community here – who introduced me to lots of useful resources (especially for grammar, my arch enemy) and 
book clubs 