Well definitely avoid King of Cats , just got released on two of the sites im usually playing on , and let me tell you.
NEVER SEEN WORSE.
as someone who grinded lil devil's heartstopper over 50x+ times. I can bravely say that King of cats is on the ban list.
site 1: took 649 spin 0 bonus (300-349)
site 2: took 773 spins 0 bonus (600-173) which is horrendous in my honest opinion.
but to say something more reletable to the topic: Dinopolis, Razor Shark, Curse of the werewolf,Fire Forge,Anubis wild megaways. these are all pretty good and volatile slots ^^
btw:loving the vids
Cheers