Bulls definitely.
All it needs is a few years of stability, growth, continuing to promote the great academy players into the first team and people will eventually forget all the rubbish that is currently going on. The Bulls brand is far more marketable and recognisable.
However I have only ever known Bulls and so am somewhat biased.
Look at it this way. My nephew is 4 years old. He knows nothing of rugby aside from when he's seen me, my dad and bro watching games on the tv. Yet whenever I am in his presence wearing a Bulls shirt he points at the Bull and asks me about it, asks why it is on the shirt, asks about why I am wearing it. As a result he became interested in my sister's old Bullman teddy which my parents still keep at their house and we have even got him saying "Come on You Bulls" when he sees the Bull.
It'll be this type of interest that will eventually get him to want to come to a game with us one Sunday and hopefully when he sees Bullman at the game and experiences it live he will want to come back and eventually start to appreciate the rugby.
I don't know that Northern would have quite the same effect.
