...Back to the original topic...
Most of the Waves plug-ins are overrated. The L1/L2 algorithm is exactly the same as Audition's hard-limiter, except for the included IDR dither/noise-shaping options (which really aren't that great either). The C1's operating algorithms are just like those in Audition's dynamics processor, but with fewer options. The noise reduction stuff in the Diamond Bundle doesn't hold a candle to Adobe's, but I can't speak for the newer Z-Noise because I haven't tried it. The Q10 isn't my favorite either, but I do prefer it over Audition's parametric EQ. The C4 (in my opinion) isn't nearly as good as iZotope's multiband compressor (which is now included with Audition, as I understand it). The linear phase stuff is sorta cool; the Waves reverbs are very good; I do like some of the "non-traditional" modules (like the Enigma), and I like the opto compressor behavior for some things. I also like the L3 a lot.
I haven't touched the URS stuff or LUXONIX, but SFX Machine does nothing for me.
That being said, I'm a big fan of everything from iZotope. Ozone 3 is my favorite and I use it for everything. It has the best EQ that I have ever used (as far as software goes), as well as the best feature set for any dynamics processor. The multiband stereo imager has its place, as does the harmonic exciter. The m-Bit dither is also the best you'll find. A lot of people love the loudness maximizer too, but I prefer the L3 for that job. The reverb sucks and is probably Ozone's weakest point.
Trash does exactly what it is supposed to do and it does it very well.
Spectron is a nice, original plug-in. I don't know of anything else like it.
...And you can get the whole bundle for a few hundred bucks!
.... I mainly use it for music production.....