It all depends how people compare it.
The Brannings as they were in 2006 and 2007 are much better than the Carters. The Brannings didn't reach over use until 2012. 6 years after they had joined. So there is the big and major difference.
The Brannings were also so popular that almost 15 million people decided to watch them on Christmas day in 2007.
I prefer the Brannings. This Dean/Linda thing for example is nothing on the Tanya and Sean thing which was similar. This is without factoring in how brilliant the original Max and Stacey affair was. The Mick/Shirley thing is lame as in comparison. Sorry but its true. That's why you cannot compare the Brannings after six years to the Carters after 8 months.
That said I don't dislike the Carters but so many of them weren't needed yet and underneath it all the storylines they have had as family aside from Johnny's coming out have been weak. Mick, Linda, Johnny, Nancy and Stan are the best of them but are being wasted mainly because there are so many hangers on in the family diluting their screen time. I honestly think if Danny Dyer quits the Carters will fold and be finished. They need him in order to survive. Whereas the Brannings could have survived, and have, without Jo, Scott, Charlie or Jake being there.