Can you list some? JBJ & DC's isn't an act to promote the fight, like we've seen with some others. But there have been other guys who truly couldn't stand each other. Which ones come to mind as topping the list as genuinely disliking one another? TUF garbage drama doesn't count.
Some of those I can think of that I thought was real strong hate, although still don't consider to the level of JBJ & DC:
- Tito & Ken
- Chuck & Tito
- Ken & Don Frye before their Pride fight, although they seemed to make up after and get along better now.
- Brock & Mir
- Faber & Cruz
- Rockhold & Weidman has grown to real, true disdain - and I don't feel it's for show. Neither can wait to bash the other any chance they get, and it's been going on for awhile now. Some of it has been pretty harsh.
Chute Boxe & BTT during Pride era
Tito and Dana
WAND AND ARONA
Ronda & Miesha
Koscheck & Daley
Andy and Chael 
Conor & Aldo although while I'm sure Aldo hated him I don't know if Conor was emotionally invested.
Bisping and Hendo
Koscheck and Daley
Great ones op. Not sure they count but here are some honorable mentions
AA vs big Tim
Bj and Hughes (now are friends)
Frank Trigg and matt Hughes
Tito and guy meztger
stcpm02 - Andy and Chael
lol
you got a scrapbook for all your wolf ticket stubs?
Nick and Mayhem.
Wanderlei vs Rampage had some serious heat too.
GSP and BJ Penn?
gsp vs bj
anderson vs vitor
cruz vs dillashaw got a little ugly
Ryan and Wallied 
Reem vs Big Foot was pretty intense
Chuck and Vernon White
Treat me like a bitch, Rashad.
Everyone vs Tito
Nick Diaz and Metabolites
Bisping and Rivera