So I just hit level 16 and I know I’ve been neglecting starting grammar/vocab building. I’ve downloaded Bunpo for grammar work and hopefully will start in on the White Rabbit Press graded readers and see how that goes. Any other resources you’ve found helpful starting to move from just kanji work into full-on language building/thoughts on these? I’ve tried Genki and some other textbook possibilities, but they haven’t really stuck like WaniKani has.
ありがと。
I’ve tried many resources for grammar, and nothing until now is quite as effective as WK has been for kanji 
However, the best of the bunch that I’ve found is Kanshudo https://www.kanshudo.com. Their flashcard system is… Kinda crap (in my humble opinion), but their grammar library and explanations are very good. Plus, they have mini-games, short stories for reading practice, etc… And they teach kanji and other things too, not just grammar.
I also would use Shirimono https://shirimono.com/, and their spaced repetition system was better than Kanshudo, but for whatever reason it didn’t really stick with me… But I am planning to go back to it soon because I learned at a faster pace compared to Kanshudo.
And oh, I’m also doing more reading practice, but I wouldn’t say I ever learnt any new grammar points from it… Basically just for fun and to see how much I can understand 
Hmmm, basically, for myself, I’m seeing that for grammar I literally have to grit my teeth and force to study it. I haven’t managed to make it nearly as ‘fun’ and ‘engaging’ as kanji 
I’m gonna give Kanshudo a try now that I don’t do WK anymore. Will hopefully help me improve my grammar and retain the stuff I learnt from WK. 
Learning grammar is very different from learning kanji or vocab, so don’t worry if you’re struggeling with it a bit more
I quite like the Marugoto courses, I’d recommend doing the Katsudoo & Rikai ones JF Japanese e-Learning Minato |The Japan Foundation They’re free! The grammar explanations are a bit… brief, so I highly recommend reading up on explanations elsewhere. (I used Wasabi, Dictionary of Basic Japanese Grammar and Minna no Nihongo grammar book, heard a lot of other people speak highly of Tae Kim as well, there’s also lots of YouTube videos, etc.) You can look up a grammar point on Bunpro and check what resources there are available for it.
You can also use the Bunpro SRS to quiz yourself, but imo that’s wayyy not enough practice.
Minna No Nihongo Hyoujun Mondaishuu is specifically aimed at self-learners I think, if you’d like a traditional practice book. All the answers are included, so you can check yourself.
Also check The Ultimate Additional Japanese Resources List! There’s a bunch of more specific resources for example conjugation practice etc.
If you can afford it I’d always recommend to get a human teacher as well, be than one-on-one lessons (italki, asao etc) or a group class
Yes to Genki and BunPro.
I’ve enjoyed using a mix of:
Supplemented with reading, in-depth articles on sites such as Tofugu and practice on sites such as Japanese Projects | Steven Kraft.
I just recently started Toucan for vocabulary building. I have also been using Duo Lingo along with it.
Toucan is working really well for me in spite of the fact that it is hella glitchy. Toucan is an addon for your browser that randomly changes words on webpages into the language of your choice. For Japanese you can set it to do Hirigana/Katakana or Kanji. The free version will only translate random words but the paid version allows you to save words to a list and set the list to “always translate these words” If you hover your cursor over the translated words it will give you the English definition and allow you to click a speaker icon to hear the word, (some of these say the word wrong but you can still read the hirigana/katakana)
Anytime I see a word I have on my duolingo list and now I’ll be adding words that have my WK kanji I add it to the saved word list so even when I’m not studying my words and kanji I’m encountering them while I’m just reading daily news articles. It’s been the perfect reminder that I need to go do my duo lingo and it’s made doing those practices much smoother as well.
Again, it is hella glitchy. I have never gotten the games part of it to work, and it seems to be permanently stuck on Kanji, but since I don’t care about the games and I only want my stuff translated into Kanji I’m not concerned about it.
Let me know how it goes! Their library is truly great, and it has many interesting points too. As an example, I found out about this just today: ら抜き言葉（ranuki kotoba) - Grammar - Kanshudo
I have spent hours just looking through the points and checking out their many example sentences. If you need any help on the website, do ask 
Yes! I will forever be grateful to Human Japanese and Cure Dolly! I’m so glad I discovered both quite early in my Japanese studies!
It might be tough at your grammar level, but try the absolute beginner book club if you’re interested in native material a level up.
Also for graded readers check out the tadoku free stuff. There’s quite a few covering a pretty wide skill range. Search | Natively | The book-reading community for Japanese language learners
Personally I’m a huge fan of Satori Reader, but I think it’s better off for people around N4 and WK 25.