As far as I know the rank Admiral was said to be the greatest fighting force of MHQ. Not specifically Kizaru, Aokiji and Akainu. Sengoku who was a Admiral himself and Garp who declined that rank shouldn't be outruled by that statement.
Greatest attack force is just the literal translation. Strongest is a perfectly acceptable one, which was used in the case for Aokiji in
chapter 303. And another adjective was used about Aokiji in the databook anyway, one that translates to strongest.
Again that doesn't automatically say they are weaker than the current Admirals.
My reference would be WB. He was shown to be stronger than the current Admirals, even though he is way beyond his prime. Means that WB was in his prime almost godlike. Just cause the Admirals are now in their prime, doesn't make them stronger than the older guys.
A bold example in Dragonball scale: Garp prime 100, Garp now 80 || Current Admirals 75, in 22+ years 60
But the fact remains that the 3 Admirals have been stated to be the strongest persons in Marines. Furthermore, Garp hasn't showcased the firepower the Admirals have displayed.
You're going to have a hard time convincing me that current WB is clearly stronger than any of the 3 Admirals. Even when WB jumped Akainu and delivered two critical hits on him, WB still failed to inflict any fatal damage on him. Akainu would later on proceed to wipe the floor with people such as Ivankov (who held his own against Kuma) and Jinbei.
Garp was said to have equal dead fights with Roger, who was said to been the true equal of WB. That is to me a much greater feat than any of the Admirals has shown us.
Garp never fought Roger to a draw. The only person who ever could was Whitebeard, and he's dead now. Prime Garp also had to tagteam with Sengoku in order to take down Shiki, a pirate in the same league as Roger, yet confirmed to be weaker than him.
This is obviously wrong. I don't know about Sengoku but Garp already proofed that he can bypass devil fruit intangibly.
Garp vs Rubber,
again. This is not like Nami's comedy punches, since it was commented that Luffy got hurt even though he is rubber.
Garp's lumps vs
Nami's lumps. Both are nearly identical and that's not factoring in Garp's nonsensical response as to why he can harm Luffy. Most of the Luffy-Garp interactions that took place are comedy-based.
Also seriously Haki is not a big deal. Sengoku who is now a Admiral in Chief (former Admiral) should by any means be able to control haki. But to be fair, it is still not clear that he can bypass df intangibility.
Also the small debate about "facts" or "guessing", tbh we are ALL guessing here. Until Oda let them fight each other. Or if a infobox is used.
Haki is very rare in the OPverse. Out of the Shichibukai, only Hancock has been confirmed to have it. Out of MHQ, I think only one character has been confirmed to have it. Out of the Whitebeard Pirates, only Whitebeard, Vista, Jozu, and Marco have been confirmed to have Haki. Out of all the high-tier fighters that exist in these 3 groups alone, you have about 5 confirmed Haki users within a group containing at least 25 high-tier fighers (Whitebeard + WB's 14 Captains + the 3 Admirals + Sengoku + Garp + 8 Shichibukai + etc.). That's a percentage no greater than 20%.