I don't really think that you can say a particular fanbase is the best or worst etc because we all have different criteria when judging fans.
For example on a personal level I respect those fans who support their team for the right reasons, back them when they are shit, and who travel up and down the country to support them.
However lets get this straight, Newcastle fans are certainly not the best fans, or the second best, or even the tenth best. They are gobshites.
So to sum it up I think you can judge individual fans but not collective fanbases.
P.S Brum fans are funny with their "who" shouts when subs are announced, and the way they unite in their hatred for the opposition is also quite impressive.