I don't know about the others, because I mainly do photo stuff ( Darktable seems decent though, and it has a been a long time since I've run linux on my desktop computer so I don't know how far it went ), but the GIMP is NOT functional in any way for a professional and a professional who is not willing to spend some dollars to get something that triples his productivity is NOT a professional.
The GIMP doesn't even support something like Adjustment Layers and that's a feature that was added to Photoshop 4.0 in 1996. Get real. Those who make that kind of argument for the GIMP, even pretending it could be used as a professional tool, have no idea what they're talking about.
Even the all-public, cheap edition of Photoshop, Photoshop Elements, that you can get for $60, has features like Adjustment Layers.
The GIMP has been working on that stuff for a long time and they're still not done yet. They put off all features related to non-destructive editing until they finally fully switch to the GEGL engine.
To be honest, I don't view Gimp as a tool for working with photos. I prefer RAW editors, and find myself surprised that you wouldn't be using Lightroom or Aperture.
In fact, I don't really see Photoshop (despite its name) as a tool for working with photos, either.
I admit adjustment layers are nice, but I don't see lacking them as a fatal flaw when there are a few workarounds and, depending on the task you're trying to accomplish, might not even be an important feature.
In any case I don't really claim the open programs are currently 'better' per se (though in one or two cases it may be true or close true), just that they're more than good enough to get decent results from.
The GIMP doesn't even support something like Adjustment Layers and that's a feature that was added to Photoshop 4.0 in 1996. Get real. Those who make that kind of argument for the GIMP, even pretending it could be used as a professional tool, have no idea what they're talking about.
Even the all-public, cheap edition of Photoshop, Photoshop Elements, that you can get for $60, has features like Adjustment Layers.
The GIMP has been working on that stuff for a long time and they're still not done yet. They put off all features related to non-destructive editing until they finally fully switch to the GEGL engine.