I started off with KaniWani after reading this super helpful guide. I used it for about a month until I found KameSame on the WK forums. I haven’t been using KW since.
Although KW has the better interface, KameSame helps with not only recall, but also how to type the kanji. It’s a two-in-one use that I personally think really benefits me. KS also has options for you to study vocab or kanji outside WK, like N5 vocab, N4 vocal etc. plus you can paste in your own sentence and let KameSame find new vocab words for you to drill on, alongside a lot of other features. However, if you like a more simple recall tool, then KW is definitely the way to go.
[Edit: I forgot to mention the synonym tolerance that KameSame has like what @iamthinking said. That was definitely one of the deal-breakers for me.]