Considering I'm posting this on renshuu, I'm pretty sure I have a good idea of what the responses will be like, but might as well post this :P
Lately I've been considering getting a WaniKani subscription, and was decently sure about it because I'm enjoying the free levels I got to try out. Now I still think it's great, but renshuu has so much to offer and yet somehow renshuu pro seems to have SO MUCH MORE Renshuu is also much cheaper compared WaniKani. WaniKani does however, seem a bit better to learn kanji with as that is what it specializes in. Also if I get WaniKani I can still use renshuu, but if I get renshuu pro I won't really be able to use WaniKani
I think I may have answered my own question by writing this post (ˉ▽ˉ；) ...
... Anyways If you reply please try to specify why I should get one or the other
I think you should take what you need the most. If you think you need to improve your Kanji knowledge as much as possible, than you should surely go for WaniKani. I just checked and it's pretty expensive though, just for kanji! If you need more than just Kanji you should definitely go with Renshuu pro since you can practice so much more. Writing Kanji(you can also study radicals here), pitch accent practice, conjugation practice, counters etc! And remember: Kanji is not everything.I personally am able to memorize Kanji pretty well even without any deepining. I hope my answer can help you choose one!
It really depends on your goals. I find Wanikani much more useful for kanji in the same way I find Bunpro mych more useful for grammar. Renshuu is a great place to practice but those apps are just much more specialized for those tasks. If you have the money, I'd definitely recommend both b
I think I will be going for renshuu pro, but if anybody wants to add something I'd greatly appreciate it anyways! Also I will add that I'm still a beginner and only started learning roughly two months ago, so renshuu pro seems to be better for that
I have a poor opinion of wanikani memory aids. They do seem to be quite popular, but I find them too erratic to be useful. Over-reliance on outrageousness, on people names, and just weird associations really turned me off of them.
However, if you do like the wanikani mnemonics, you should know they are free to view. Wanikani only charges for the spaced-repetition-system (SRS). Renshuu also has an SRS for kanji, and it’s free.
You can get everything WaniKani has (and much much more) at Renshuu for free. Despite kanji being WaniKani's specialty, Renshuu offers way more on kanji too (more kanji, more vectors, more mnemonics, way more flexibility).
If one were so inclined, they could create the same experience that WaniKani has here at Renshuu. They could create kanji and vocab schedules that matched the ones that Wanikani uses. They could set the vectors on those schedule to match what WaniKani uses. They could even use the same mnemonics that WaniKani use for the kanji.
That being said, one probably wouldn't want to limit themselves that much. One would probably want to take full advantage of what Renshuu offers.
If you get Renshuu Pro it unlocks even more amazing features and cool ways to learn kanji (additional styles of kanji reading questions, and the writing practice vector).
Of course, Renshuu also does vocab, grammar, sentences, listening, conjugation, games, etc...
As someone who has lifetime for both, let me give you my opinion.
I discovered WK first and used it for about 3 years. I went up a little bit over LVL40 and then called it quits.
That being said, in the 3 years I got my money worth for the lifetime, I don't regret getting it (I could comfortably afford it though).
One advantage Wanikani has is it's extremely approachable and motivating for new learners. It has a clean UI, and there's lots of Userscript to improve your QOL experience.
While Renshuu should be able to do most of it, it's just not the same experience, the way things are presented to you on a silver platter. Some might need that, others might dislike this babying approach. I found it helpful and learned about 1500 kanji there, N3-N2 level.
However it made me neglect other forms of study, mainly grammar and vocab. This is how I found Renshuu which offers SRS for everything for free. Another downside was that mnemonics didn't work well after let's say level 30. The kanji get too difficult and abstract. It's better to learn the readings from vocab and read a lot.
Nowadays you can import your kanji from Wanikani (experimental feature) or there's also some user made lists, you can make the quizzing settings similar. So I think you would not need both. However I still see the advantages in using Wanikani if you want a very streamlined service with no distractions and the book clubs are also very active in that community.
Renshuu is also much cheaper compared WaniKani. WaniKani does however, seem a bit better to learn kanji with as that is what it specializes in. Also if I get WaniKani I can still use renshuu, but if I get renshuu pro I won't really be able to use WaniKani 
I personally am able to memorize Kanji pretty well even without any deepining. I hope my answer can help you choose one!
