FULL DISCLOSURE: I'm the main author of Kanji From Zero! so my review is possibly biased although I am trying not to be biased.
Kanji From Zero: https://goo.gl/yebH99
Complete Guide to Japanese Kanji: https://goo.gl/JFqhfg
Kanji Learner's Course: https://goo.gl/dHdcWz
Remembering the Kanji: https://goo.gl/uzn4hQ