One time famous pianist John Browning (now deceased) said that he tried numerous ways to memorize, but what worked for him was playing the music over and over until he eventually no longer needed the score.
That's pretty much how it is for me, with the caveat that I MUST really like the piece and find an emotional connection, i.e. MY vision of the piece.
If I can't do that, I can't memorize it.
Having said all that, now I'll contradict myself.
Sometimes, eventhough I like a piece in terms of hearing a recording, it is slow going trying to read, make sense of it, discover the fingerings, etc., etc., etc.
Rachmaninoff is a good example in that it can be so dense, in so many keys, literally all over the keybord and not at all self-evident until you get to a certain point of proficiency with it.
Which means, even though I don't "like" the slow slogging of this somewhat miserable and mentally exhausting process trying to chop through the jungle of notes and assimilate complex works, its simply necessary to hang in there or I'll never "see the light at the end of the tunnel".
But this is a very individual thing, and in the end, its the performance that counts, not how you got there.