Yeah I'd say Danzo is far more cunning and vile, for two reasons mainly, Danzo was always the underdog in the hokage race so he had to work behind the shadows, and the second is Narutoverse being a more intelligent world than OP. Kabuto's flashback and how Danzo manipulated the scene was as brutal as it gets, Akainu doesn't have to be as crafty to get what he wants, he charges straightforward at it.
Sakazuki still does wicked things like bombing the Ohara civilians, even without orders to do so, that's precisely what his thorough justice is about, but the difference is Saka was angry giving the order, Danzo on the other hand feels no remorse whatsoever. With that said, Danzo is still a farcry from the Gorosei, as his actions still stem from good intentions, but he definitely makes Akainu look like a rookie lol
The actions do benefit Danzo's power directly, naturally since he believes only he could fix the village. Still counts as non selfish reasons.