What does "sounds digital" mean? That is something all fractal users say about anything.... which is a direct quote from the inventor of the axe fx. Opinions are great, but at least say something that is an actual description. Nearly all, in some cases literally all, of the music you have listened to over the past couple decades is digitally processed. Orchestral recording engineers embraced digital when it came out because of the increased S/N ratio, dynamic range, and accuracy. Fractal audio's gear is equally digital to line6 or zoom or roland technology. They are all 100% digital, aside from the obvious analog buffers.
I do personally feel axe sounds amazing... mostly axe 3, but also axe 2, heck even the axe 1 sounded amazing. Line6, on the other hand, invented the technology, so you can't write them off since everything fractal does is based on technology invented by line6 engineers.
I find Axe is warmer sounding, by default, than the helix. I love both.... I personally am using helix currently but might grab another fractal unit soon since I love them too.
But... "sounds digital" is an absolutely, entirely meaningless description, right out of "audiophile" worlds where they claim the terrible LP record actually is more accurate than a cd.
What "sounds digital" used to mean was converters running at too low a frequency, so the high end was cut off and distorted. That hasn't been a thing since the 1980s.