The truth be known, I was at one time a 49'ers fan. But that was back in the mid 60's, and SF was the closest team geographically to where I lived. But at various times during the 60's and early 70's, I was a Cowboys fan, a Dolphins fan, and a Chiefs fan. The teams I couldn't stand back then were the Packers, Rams, and Raiders. All pre-1976.
As far as current day goes, although I had long since given up the Cowboys as a personal favorite, I'll never forgive Jerry Jones for how he dumped Tom Landry like he was yesterday's newspaper. And I don't like the way he micromanages his team. I see him much as I saw George Steinbrenner of the Yankees. So long as he's the owner, I'll hate his team, first and foremost.
As far as the Niners goes, I hated them when Harbaugh was there because I regarded him as a first-class A-hole. Now, want to see them lose if it is to our benefit, but I don't have a voodoo doll I'm sticking pins into, either.
The rest of the league I'm pretty neutral on, except, of course, as it relates to our Hawks.