I’ve used WaniKani for years (I’m on my 2nd time going through it all), and my biggest wish is still that the “visually similar kanji” feature was more thorough, and honestly, that they would be shown prominently when first learning a new kanji, not just when viewing that kanji’s page.
So many times I have to open a new tab because I’m like “Wait, how is this any different from that other one I’ve learned?”