FATEs do seem to be the best source of exp by far, but I don't get why so many people who say they hate it still FATE grind for hours? Is it that important to level up to 50 ASAP? If it is, then why complain about the fastest method. If it isn't then why not diversify? Queue up for dungeons while FATE grinding, do some leves, etc. It may take you an extra week to level, but if you really hate FATEs that much, its not worth it?