Not 1 easy answer for this one....
For mix compression for rock mixes I have used/tried (over the last few years)
-Neve 33609
-Chandler LTD-2's
-Summit DCL200
-Drawmer 1969
-SSL bus compressor (most of the times with a highpass on the sidechain)
-Tubetech (the multiband)
-Fatso
-Manley VariMu
-(and stuff I forgot about)
....it really depends.... But the last two years the 1969 has become my favorite for (heavy)rock. Sometimes I combine it with a touch of SSL or some Fatso (no compression, no tranny... just some saturation)... or a bit of both...
Others listed above also worked... although I am not a big fan of the TubeTech multiband and Manley Vari-Mu for 2bus....
Just my 2cents