Not exactly considered a "mastering" compressor, but I like the Waves Renaissance Compressor and the Focusrite d3. For quite a while now, both of these, have really been work horses for me. I've only owned the WAVES SSL 4000 COLLECTION for about 2 months now, and I don't feel I've used it enough to make a determination, good or bad for now. Last weekend I did some experimenting with the SSL channel strip, and I believe with a little work, and getting used to, it will be usable for me.
I've owned the URS EQ plugs for quite a while now and have grown to love them, especcially the FullTec. I've not used any of the URS compressor plugs yet, does anyone have any experience with those?