Well the action genre is pretty large so I don’t know what kind of action series you are searching for, but I compared our lists and saw that you haven’t watched Shingeki no Kyoujin, Arslan Senki, Nanatsu no Taizai, Black Clover, Psycho Pass, Noragami, Koutetsujou no Kabaneri and the Fate series yet, for instance. They all are more or less action but with very different second genres. Maybe you can find something you’ll like :)

And one more thing: If you click on the tab “Explore” and go to the right upper corner and click on the second button from the left, you can explore the genres. Click on “Action” and you will see all anime tagged with action, sorted by popularity (if I’m not mistaken).