Guitarhacker
All that may be good and well.....BUT!
As I see it, I have favorites when it comes to EQ. Some are just easier to work with and make adjustments and yeah.... to my ears, they sound different too.... maybe it's my ears fooling me...
That's my unscientific observation.
That is the best observation of all.
Like Rain said, after the fact if it's pure EQing that's happening, without any of the analogue emulating saturation and distortion that might be inherent in your plug-in, you can get to the same place with pretty much anything.
A major thing that can be overlooked when looking at mere technicality is that some suit or impose a way of working that makes the job more efficient and less of a headache to get done. Sometimes defaut frequency positions, specific Q curve adjustments just play right into an individuals way of working or can even impose a way of working that brings great results quickly and can strongly contribute to an individual 'style' in the sound shaping process.
Take an old style hardware EQ like a Neve 1073 for example, the reasons it was so popular was BECAUSE of it's limitations not despite them. It had carefully chosen frequency bands which were switchable, not infinite adjustements like many plug-ins and once you've got mastery of it you could knock a drum kit into the ball park of sounding great in seconds and it caused a lot of mixes and sounds of the era to have a particular and similar sounding 'style'.
The technical aspects are one thing but they don't tell the true story without taking into account how they are implemented. So to that extent at least they all differ greatly.
I certainly have favourites, with good reason too, and I stick with those by and large.