In the end, in my experience, it comes down to a few things:
- stability and available support for problems - ability to share native sessions w/ other users (as opposed to just stems) - support for hardware (audio i/o and controllers, including mixing surfaces) - ease of use - so the interface and process doesn't get in the way of the creative process
I am not necessarily a fan of ridiculous skeuomorphism in things like plugins, but at the same time a big knob or fader on the screen makes a lot more (and a lot quicker) sense to me than a little box w/ a hex value in it. I think the advent of touch screens in pro installations reinforces this - see Slate's Raven controllers, which are becoming very popular now - http://www.slateproaudio.com/products/raven-mtx/
In the end though this is just me - more power to anyone making good music anyway they can.
They improved the looks but there was always something that didn't work quite right. IN the 3.x series Midi was introduced, but it crashed all the time (and I've updated every time there was a new release).
Now I am using 4.x and it is dog slow for big sessions (which I originally recorded and mixed in 2.x on a much lesser PC with no problems).
I do understand their arguments. I know that they want to release something for Windows, Mac and Linux to improve their customer base (greatly). But I really hope that Ardour solidifies and they start improving the quality that it comes back to the quality of the 2.x releases.
It was totally normal that Ardour crashed at least twice in the 1 or 2 hours when we were editing drums. And the devs knew that this problem existed, but they've basically told, that it should be fixed in 4.x.