I've tried several types of software, but the only one I've returned to again and again is 暗記 Anki. (link here). They also have a iPhone/Android app that syncs with your computer.
Interesting piece of software, that I haven't seen before. How hard is to import data to create your own cards?
Import? You mean from some other kind of SRS software? Never tried. I've either downloaded pre-made decks or built my own the entire time. The "shared decks" feature offers a wide variety of things to study; from GRE vocab, via organic chemistry, to the entire set of JLPT1 kanji
Creating new cards is super easy though, the only thing that might take a bit of fiddling is making the card template if you want to have your own, difficult, stuff. I have a deck where the cards look as follows:
Top line: kanji/hanzi/hanja (simplified + traditional if available)
Middle line #1: Kana reading (on- plus kun-yomi)
Middle line #2: Pinyin reading
Middle line #3: Hangul reading
Bottom line #1: Meaning
Bottom line #2: 3 common compound words using that character
I only have something like 260-280 characters in there atm, planning on expanding to ~500