A friend and I decided to build an Anki replacement a few years ago, it's now located at https://www.memorangapp.com and has a loyal following of 10s of thousands of users. Anki is a great tool and has a wide variety of content on Ankiweb, however the ecosystem doesn't allow for any collaboration or the ability to keep content up to date (aside from manually editing decks, but where for example can you suggest a corr…
Totally agree, spaced repetion has its role but has huge limitations. The limit of most programs is that it has you learn in a unidirectional manner, so very few memory pathways are formed and they are easily lost/degraded with time. As an post states, the flashcards didn't stay, but the characters you learned while in Japan stuck. I submit that part of that is that this material was presented to you in several ways (signs, books, TV, etc), rather than just flipping a card over and over. I've started using Memorang instead of anki, as it allows me to retain information in the long term, as it has multiple ways to approach/learn the same info.
Add the fact that it's free to generate your own content which is perfect for me (speaking as a medical stuff with thousands of facts to not only memorize but apply)