If anyone can think of better fruits or something please state the fruit then the reason why.
I won't be listing them in order of which I believe is best but here I go.
First off I believe Rust is a very effective and insane Devil fruit. It Can turn anything it touchs into rust and then rust into nothing but dust. Therfore touching someone or something could be deadly with the smallest touch. Now imagine a Diamond blade infused with a Rust Devil Fruit by the Scientist. Any kind of metal or anything that blade came slashed would rust and be easily cut by a diamond blade.
Second I believe a Nova Fruit would be Cataclismic. Think about it, the destruction force and energy behind a Nova star or Nova anything is insane. Therefore say someone with the Nova fruit was about to die. He could as his last breath descide to destroy the entire world or universe.(The sun can go Nova and wipe out 75% of the universe or more) Thats an example.
Thirdly the Light fruit by far is a Beast no doubt. Speed of light is so crazy that appearing out of nowhere would be cake, shooting lightbeams could not be dodged, and getting cut,punched,stabbed,kicked or anything would have no effect without a Fruit Power of some sort.
Another one which is a favorite even though isn't so powerful.....or so I think is Anti Matter. The story of anti matter or insane thing about it is this, nothing can occupy a space or be in the same spot as something else. Unless of course your a ghost, which is anti matter
One power i found interesting would be Vacuum as well. The thought of being able to create a vacuum around a person is demolishing. May not sound like much but within a vacuum all air and such would be sucked out of you in an instant.....causeing a very painful death.
Nevertheless I Believe one of the deadlist and most powerful element Devil fruit would have to be water. Now Most would say fire but think.....Every liveing animal and human has water in them, every plant has water in it, and even the air has water in it. Now if you could manipulate Water you could control whoever and whatever you like. If you wanna see someone do a backflip manipulate the water in their body and make them do a backflip. You wanna kill a Mean Beasty, Just manipulate the water to leave his body and watch him instantly fall to the ground. An Say someone attacks you with fire or something, you ate the water fruit you could mix in with the water in any surrounding that you like. Oh Yeah, Heres the best part......your water and you can manipulate water, Do like Moses and seperate the water to clear a path if you like. There goes ever drowning or being weakened by water.....cause you are water
Last but not least just a quick thought but a Weight Fruit has to be insane as well. Consider everything you touch you can double its weight. Or say someone attacks you and you whisper 10k well unless that person can kick a 10,000pound rock out of the way then his foot will be broke lol.












