I like the URS CSP. If you want to get close to the waves SSL sound without forking the bucks, there are some presets for Logic's stock compressor which can get scarily close. Maybe worth a try if you are on logic?
Waves G-Master Buss Compressor (my usual setting for mid-tempo metal music - ratio 4:1, attack 30 ms, release .1, gain reduction about 4 db or so, analog mode on)