Well, ngl this was to be expected. I've always said Sabo and Ace are two of the most underrated characters out there.
Marineford Ace => Marco. Imagine 2 more years. Ace would be 3.5 by now and he would have been able to take out Big Mom by himself quickly catching up to Kaido too.
Ace had an extra gear similar to Luffy when his friends needed protection that Sabo obviously also has but probably to a somewhat lesser degree.
What Sabo has is the fortune of becoming a Haki master first before getting DF, that way he didn't fall in to the same trap as almost every other DF user that relies too much o their fruit before realizing they need to up their haki as well.
Dragon surely is former Admiral White Dragon, 6B (strength + going against WG). Akainus true rival.