A little hard to say objectively as I only attend our games against those grubby f**king frauds.
From memory, on the basis of attendances against aforementioned frauds us, Parra, Manly and Tigers. Storm seem to have a decent following as do Souff$ but in my experience many Souff$ fans switched to the Broncs and have only switched back since Rusty bought them enough outsiders to become competitive.
On the basis of seeing jersey/hats, Parra, us, Manly, Roosters and Souff$ although the Roosters and Souff$ stuff is only on display when they are contenders.
For some perverse reason, I am more inclined to wear a jersey after we have been beaten.