What I meant do you really think Enel would be as powerful as he was if he had darkness logia instead lightning logia?
Darkness logia is perfect for someone physically as strong as Blackbeard, but if you give that power to other people, they may not be as powerful as before, even Admirals in my opinion wouldn't be as powerful as Blackbeard with darkness logia, that power is perfect for BB, but for others? Not so much.
BB said darkness is the most ''dangerous'' ability, in different translation it says ''most evil'' ability.
https://mangahelpers.com/t/skywalker6705/releases/6199
Gura is again, I believe the most dangerous ability like darkness, I don't think they said Gura is the strongest paramecia, Oda said Gura is on the same level as logia, but still there are other paramecia powers like that equal to logia as well.
I believe Ope Ope no mi > Gura Gura no mi.
But in terms of danger to the environment, Gura is the most dangerous due to creating earthquakes and tsunamis, while Ope is said to be the ''ultimate devil fruit'' power. Also there are powerful paramecia abilities like Doku, Kira (Diamond), Invisibility, Kid's magnetism etc. Especially abilities like Diamond or Invisibility gives defensive advantages too, while Gura doesn't give any defensive advantage to the user.
Oda says ''one of the'', not ''the'' most powerful paremecia, it means there are still equally powerful paramecia abilities to Gura;