Media and fans, but with explanation:
I hate the teams whose media and fans I'm over-exposed to. I'm a Habs fan. Live in Vancouver. My TV sports media consists of TSN and Rogers Sportsnet (which focus too much for my taste on Toronto sports franchises). Hence my "hate" for the Leafs, Blue Jays, and Raptors. The Toronto CFL franchise - the Argos - isn't "over"covered because they don't have much of as fanbase, therefore, I don't hate them.
I don't have a smartphone, so my media is pretty traditional. Living in Vancouver, if I wants sports radio, I have 1 option and the station is virtually 100% Canucks when it's airing local stuff. The 2 local newspapers basically cover only the Canucks and the rest are stuff from wire services like Canadian Press and Postmedia, which means a lot of Toronto-based team coverage. When the Canucks made the playoffs this year, every local radio station and TV station would have coverage/stories. Difficult to avoid.
Neither the fans of the Leafs or Canucks bother me because I don't over-expose my self to them. I don't read comments on the Leafs board. Basically, I read only the thread about media on the Canucks board and only for certain posts/topics.
I have nothing against the players on the teams I hate. I'd rather have had the leafs' players on the Habs in the past 5 years. Going forward, I'd rather have the Canucks' roster than the Habs' roster.
I don't hate or strongly dislike any other teams in the league because I don't overexpose myself to their media. I'm sure if I watched the pre-game shows for say, Minnesota, the intermissions (local broadcasts), listed to local Minneapolis sports radio, read Minneapolis sports pages, read the comments of Minnesota fans on HFs website, there's a good chance I'd develop a hate for the team.
Until regional broadcasts of Habs games became available here in BC (TSN2 or streaming), and websites like HF with fans' comments, there wasn't really anything I "hated" about the Habs. Now, I've developed a major dislike/hate of some of the broadcast team on the regional broadcasts as well as MANY of the habs' fans who post on social media sites like HF.