Morality, Character & Ambition
Sengoku has never shown any ambition besides fulfilling his Admiral/ Fleet Admiral duties. He cares about upholding the law because it is his job
Sengoku ordered the Ohara buster call, did he do it because he thought it was right? That's most certainly not the case. To Sengoku, government orders are the words of god, to some extent "Government Dog" suits him the most
Sengoku was also involved in the killing of any pregnant woman in contact with Roger, likely among countless atrocities we are not aware of
His reactions to Whitebeard's last speech and Vegapunk's speech are also telling of what kind of a man he is
Now he might have gone soft with age, but that doesn't cancel the kind of man he was in the past
As for character, even though Sengoku is supposed to be the only CoC user, he sure was portrayed as a paranoid faint hearted soldier, contrary to Sakazuki being a tenacious and confident leader. In Marineford, this was portrayed clearly
Sengoku was a competent strategist in Marineford, but failed big time as a leader. Luckily for the marines Sakazuki was there to take the mantle
In countless panels we see Sengoku acting weak and indecisive
Whereas Akainu was raising morale and thinking of a plan to reverse this loss
When Blackbeard obtained the Gura, we see Sengoku shitting bricks
Meanwhile Akainu gave him the "I'm coming for your ass later" look and continued pursuing Luffy
Akainu even amidst this chaotic era is still as confident as one can be
When it comes to ambition, Sakazuki has his own goals, he is hellbent on destroying piracy. This is what drives him to uphold the law unlike Sengoku who is doing it for his office job. When Sakazuki bombed the Ohara ship, he did it out of principle.
He is as passionate about destroying piracy as Luffy is about becoming the Pirate King. Sengoku never had such resolve.
Akainu is the type of dawg to walk into the Gorosei hall, light a cigar, mock them to their face and even give them an order
Meanwhile Sengoku
It is no wonder that the marines under Sakazuki's leadership are stronger and more determined than they've ever been
Moving HQ to the New World is also a ballsy move that Sengoku would never commit to
In conclusion
-Akainu is a stronger leader than Sengoku
-Akainu works on principle and ambition unlike Sengoku who was more worried about the Government's approval
-Akainu is individually stronger than Sengoku
Basically better than Sengoku at everything
"B-but Sengoku has CoC"