You want to know what makes leaf fans annoying?
Geography my friend. It's because we live in Toronto (or the GTA of you will) and hence that's the team that gets exposure. We are not exposed to Habs fans or Penguins fans to the same extent because of georgaphy alone.
The truth is that Leafs fans do nothing really that fans of other teams aren't guilty of. Take Raptor fans for example. I can attest to the fact that they're annoying too.