Well, I misclicked and chose MM3.
But my favourite is of course LF3. MM3 is very entertaining and well thought, has awesome artworks and music, but there's only so much a 20 hours long game can do - it will never be as epic and thrilling as LF3.
And another thing - LF3 is more rewarding in the sense that you can spend lots of time searching for all the relics or trying to win Arena with all the characters and so on, and then have the feeling of some accomplishment when you actually manage to do this. MM3 cannot offer this imo.