I don't think Furman's are the best nationally by any stretch but
Oldest, the Citadel. played since the 30s and was pretty even until the 80s. Important differences for a rivalry. Low country versus upstate. Military versus up scale private (and in years past baptist). Storied not only in reality but in literature as Pat Conroy has enshrined some of the rivalries greatest moments, including the horse that was kidnapped (and blinded) by the Cadets and the Cadet raid on Furman that was foiled when a Highway patrolman alerted Dr Bonner of their impending arrival on the FU campus. The few cadets that made the trip were apparently greeted at the entrance by a very large welcoming party. Taft ruined the rivalry by changing the play date from the last game of the year to the middle of the season because he didn't want to play Furman prior to El Cid going to the playoffs.
Current biggest would be GSU. Important parts told above by a different poster. First two times we played were for National Championships unfortunately on the other side of the country. The problem with this rivalry though is that it appears to be heated only when the teams are at the top of their game and in their division. Doesn't mean we dislike each other less, but it loses fire when we aren't playing for something more than just the game between us.
Future rival I think will be Wofford. Wofford folks hate us probably because they spent years in the shadows playing NAIA and DII. Furman fans still can't quite muster the hatred for the l'il dogs but I think that will change the longer WC and Furman play every year and as long as the series stays competitive. Another good basis for a rivalry (different than The Citadel) is the similarity. Small schools. Religion based. Similar academics. proximity. Both upstate but the rivalry between Greenville and Spartanburg adds fuel to the fire. Of course Greenville wins that one hands down and hopefully Furman will too.
But the rivalry isn't quite there yet because the hate is still too one sided.
