No way Brian improved AC/DC, Bon was the best ever. Especially if you listened to some of his pre-AC/DC stuff with Fraternity, very unique voice.
He was really good. I like all ACDC. But Back in Black is the one people know and love. It’s Zep 4/Dark Side for AC.
People may disagree about who was ‘best’ and it’s all subjective anyway. But BIB has the sales figures. And most of the songs thought of as ‘classics’.