Honorable mention to the Atsu Atsu no Mi. The fruit is non-canon, but good lord it's actually somewhat of a nice fruit to have. It's like Oven's Netsu Netsu no Mi, but more powerful and relies mainly on if you're calm or mad. Don Accino in the anime is completely immune to any type of heat, freezing temperatures, or even molten lava itself which is pretty broken which not even the Mera Mera no Mi can permit. It's also known that if the user is mad enough, the fruit will affect the surrounding environment and can even wake up sleeping volcanoes. The filler arc itself was somewhat good imo, but good lord the devil fruit that man showed during that filler would be even more busted if it was in the hands of a top tier like Whitebeard or Kaido.