@freedom:
You seem to be constantly missing a valuable point here regarding DFs.
The DF is only as powerful as the owner of said fruit.
If someone like Vivi had the earthquake fruit, her attacks would probably at most shake a room. However, the same fruit in the hands of someone like Zoro, we'd expect him to shake up a much much larger area.
Freedom, while I agree with the initial premise, the earthquake fruit handles pretty fucking awesome with a man who´s a first timer with it.
I know BB is strong, but the fact that he can create an earthquake that looks pretty much as strong as WB´s on his first try would insinuate that the earthquake fruit has a ridiculous base strength from the get-go.
Also, an earthquake is an earthquake, it´s not a tremor or a replica. It´s a fullblown earthquake. And we have seen that the fruit actually creates earthquakes. This means that the DF itself operates in the Megaton ranges of energy output. SGraaize, though dense, does have a point in that the earthquake fruit is stronger than most fruits. Even Sengoku says something akin to it being the strongest or most dangerous fruit, I can´t remember.
Bottom line, the earthquake fruit is insane. I´d say, give it to someone like Vivi and she would perhaps not be able to direct or focus it, but she would also be able to make an earthquake. It´s in the name of the DF. She would however probably be overwhelmed by it, or tripped, or even open up a schism and kill herself. It´s so powerful it requires someone as powerful to handle it.
For instance, it´s one thing if Mr.5 has an explosion fruit, and another if he has a nuclear explosion fruit. If he had a fruit called the nuclear explosion fruit, then I´d argue that his little booger would create a nuclear explosion, not a mini explosion like the ones he is able to create. Of course this would be ridiculous, but it´s also in the megaton range, like an earthquake, except the earthquake fruit actually exists, hence it´s ridiculousness.
For the rest of the fruits your statement is untouchable, I think. But the earthquake fruit is in a class of it´s own, since well, it instantly gives you the ability to create earthquakes.
WB has the amazing ability to direct it´s power, to tilt an island with that power, and to concentrate a quake´s power within his fist. When you consider just what he is subjugating, that is the strength of multiple nuclear explosions, his skillset with his DF is pretty damn impressive.
So, my final point is that while the initial base skillset of the Earthquake fruit has the most energy output, which is to create an earthquake, it takes just as much training to use it in battle properly, if not more than other fruits due to the sheer incomprehensible power it has.
In the end it´s hardly a different point, except that not being able to control a spring fruit is much less dangerous than not being able to control creating earthquakes.