I really like MIOComp, but I'm not sure that qualifies as a "plug", since it runs on +DSP in MIO-land. MH Channelstrip's comp is very similar and something I use pretty freely when I'm working native, or don't have an MIO handy (rare to never)... CS has some modes that are unique to it and not obviously there in MIOcomp, but the knee control in MIOComp covers those functions, with even more flexibility. Still, I could use CS and not wince or whine.
I also like the sound of MasterComp, and sometimes return to Waves Renaissance Comp for specific color. At my old job we had LA2As I used all the time, but in the tracking/mix room I use these days they have UAD versions which sound very good when properly gain-staged (plugs respond differently to poor levels than analog, no matter what the mfg says). I still use their Distressor, LA4 and DBX 160 in tracking and mix sessions for specific colors, but honestly it's as much matter of convenience as sonics - If I want to dig around the plug-list and tweak forever I can get the same sounds or better via plugs. I'm not a snob, just lazy, at least for tracking/mixing, when musicians are in the room to get work done.
I use Ozone 4 at times to do things analog hardware cannot do at all. I like the SSL models from UAD, but again, MH MIOComp sounds more real, maybe just more like an SSL to my ear, at least as far as the color of the compression goes. YMMV, just one MEs take on plug-in comps.
-d-