Akainu have a beef with Dragon because he keep calling Luffy with "Dragon's son".
So its safe to say Dragon is as strong as Akainu.
Akainu called Luffy Dragon's son because Dragon is the world's most wanted criminal in history.
Luffy was, at the time, a mere rookie like many others.
Which I find funny because a "mere" rookie took down 2 Shichibukais, who were supposed to be this big trump card for the Marines, to counter the Yonkos...
And two of them got taken down....
We hear about the other supernovas "doing stuff", but, aside from Urouge who managed to beat a Sweet Commander, none of the others have any actual achievements.
Law has some "Rocky Port incident" or whatever. But they never tipped the scale of the world order to be any special. Worst Gen hype is build by Oda telling us "they are important. trust me, bro".
BB at least did things that actually impacted the world's balance, like taking over Whitebeard's place as a Yonko, breaking out some of the world most dangerous criminals, etc.