I find Laker fans to be the hardest to argue with.
In the bigger picture, the sports fans that are hardest to argue with are the ones who don't have any of their own opinions, but who just regurgitate the opinions of the "experts" (see: 90% of the Renaldo Balkman bashers on draft night). I have one guy in mind specifically. Whenever I talk to my friend's father, no matter what I say, he replies with, "Well I think the general consensus is..." or "Well what most people are saying is..." and if I disagree with "the general consensus" or "most people," then it is just as good as me being plain wrong.
That being said, I find that a lot of Laker fans don't really know much about basketball or the NBA. In addition, many of them refuse to see different points of views. Something about the Lakers attracts these kinds of people I guess...
I think the reason why people are sayin the Raps and Lakers fans are the hardest to argue with is that they have the most fans on this board. Just look at the amount of posts on their respective team forums. The more people you get on the boards the more diluted the opinions will be and I am a Raptor fan and I have to say we have our share of bad posters who don't use knowledge and common sense in their posts but we do have our share of good posters. I also think some of the raptor fans get some s*** for liking our team, whenever we say our team is good we get shot down and I think the immature posters start going crazy. We are not number 4 in the East by a fluke, we earned it but thats another story right there. I can't speak for the Laker fans so I have to say because of the shear amount of posters the Raps and Lakers fans are the hardest to argue with. Gonna be a good play-offs this year!