I also prefer WaniKani but I wouldn’t want to miss Anki (the premade decks, often with native speaker Audio; subs2srs; importing cards from various sources; huge amount of customization options; bulk import from csv files => I just love it). But Anki out of the box isn’t all that great, you have to think about how you use it to get the best experience out of it.
Some of the things that most improved my Anki experience:
1.) Most important, I believe: https://vladsperspective.wordpress.com/2017/03/14/optimize-your-anki-youre-overtesting-yourself-on-too-few-cards-make-huge-gains/
I use just Pass or Fail now and just ignore the Easy and Hard buttons (unless something is really super easy because I know it already but for some reason don’t feel like suspending it). That does make my reviews easier and more relaxing.
You don’t have to install any plugins to do this if you don’t want to: just ignore the other buttons. If you are reviewing on your phone, set your app up so that clicking on the right side of the screen is “correct” and the left side is “incorrect” and that is all you ever do. Significantly increases the review experience in my opinion.
2.) I just tag my leeches automatically, not suspend them. Suspending leeches made me click “I know this” too often because I was afraid that I would “lose” my card.
3.) Another thing that helped me enjoy Anki was reading about Cloze cards and that each card should have exactly one piece of information that you can get either right or wrong. Not much thinking when there is just one word, particle, kanji… that you have to fill into a blank instead of translating a whole example sentence (which is what the Genki deck that I had downloaded was set up to do initially).
4.) I focus on Recognition (JP => EN) instead of Production (EN=>JP) cards to get more input. But the Genki deck is an exception because this is still beginner stuff and I should be able to produce these items. This gets more frustrating as you go on because there are just too many ways to say things (unless you are using good example sentence and cloze cards)
5.) You also have to get used to flashcards in general. Really think of the solution, preferably say it out loud before showing the answer. When you say it out loud (at least in the beginning), it’s less easy to cheat. There is nothing to think about (did I get this one right or not?) and this again makes it easier. I’m also doing my WaniKani reviews this way with the Anki script (modified for mobile so that it has buttons, there’s a thread for it somewhere when you look for Android scripts).
6.) About the core deck: The way I use the core deck (an Anki classic) btw is that I only have sentence listening cards set up. I listen to the sentence, try to translate it and as long as I get the main vocabulary item right that is being asked for on that card (not the whole sentence because some are still too difficult for me), I pass that card. This way I also practice listening at the same time.
Also, I imported all WaniKani items with their level infomrmation (there is an exporter somewhere on the internet) as tags. That makes it possible for me to e.g. only unsupsend core cards for items that have a certain WaniKani level.
And when you say “Genki deck”, I hope you have the version with native speaker audio recordings? There are so many decks out there but in my opinion, that is the best one. I find everything so much more memorable with good audio.