We don ' t have actual percentages but Blizz has said in the past , that the higher mythic have a higher drop chance . This could be super trivial though . Most people will tell you that mythic is the best way . Despite there being less overall loot , you can only run regular mythic dungeons as loot eligible once a week , so you get one shot at a legendary per dungeon per week . With mythic you can run the same dungeon over and over again so long as you can keep finding a key . Putting together a group of four people and pugging in someone with a favourable lower tier keystone is what most competitive raiders do to farm AP and legendaries . It ' s why there ' s effectively a market for maw 2 keystones , since the dungeon takes about 9 minutes to complete . As a regular mythic , you can only run it once and get loot . you can run it as many times as you want , but won ' t get loot or shot at a legendary in any subsequent run .