Ohio State, Texas, Oklahoma, Alabama, Notre Dame, Michigan, Florida, USC, FSU, LSU. It's kind of tough to judge, it depends if we're going historically or currently. It varies as well, for the state of Florida in particular like the top comment said. I'll always hate UF and Miami obviously but right now FSU is holding that torch in the state.
Especially for Miami, they haven't been good for a while. I know we use this as trash talk a lot, but they really haven't played in a conference championship game since joining the ACC. That's crazy, it's been like a decade of competing against Duke, GT, VT, UNC, UVA, and Pitt. And Pitt just joined in 2013, I'm pretty sure they moved the location of the championship game because of "The U" not being able to win the ACC Coastal ever.
But they don't call them "The U" for nothing, that team gets possibly the most hate out of any team in CFB when they're on top. They've got two separate documentaries on their historic runs. The first one was for like 10+ years. And the second one was only 3, but they were so good those 3 years that they made a part II. Which of course includes the 2001 Miami team which is arguably the best CFB team ever.
As for Florida, I left them on the list because they were ranked like #3 at the end of the regular season in 2012. Also, the Tebow era didn't end that long ago, so they're still in the league of evil. For me, they are my original hate because my earliest memories of being an FSU fan are 1996. FSU took it to Miami that year and it was kind of a going away party for "the U" since I believe they had some sanctions hit them over the next few years.
But UF was #1 for most of the year, and it was such a great day watching FSU jump out to a 17-0 lead and hold on for dear life to win 24-21. It was such a relief! But of course that wasn't enough, we had to play them again in the Sugar Bowl and this time it was for the Natty.
And we got worked, in a game that was EERILY SIMILAR TO THE ROSE BOWL AGAINST OREGON THIS YEAR NOW THAT I'M THINKING ABOUT IT, WTF. Seriously though, it was 24-20 about halfway through the 3rd quarter compared to 25-20 halfway through the 3rd against Oregon. Final score of the '97 Sugar Bowl was 52-20 compared to 59-20 in this year's Rose Bowl.
Anyways, that sucked and then in the '97 season the #10 ranked Gators knocked off #1-FSU 33-28 in the swamp. Once again ruining FSU's chances at a national title. So UF was my most hated FSU rival while Miami was an afterthought for a few years. However, a wide right and a wide left caught Miami up REAL QUICK.
TL;DR- I hate Miami regardless, but they get more hate than anybody when they're on top. My original hated rival is UF and I give an example as to why. I wrote more words than I was planning on.