I owned an Audya for a year and a half, and now own a PA3X. They both are outstanding instruments and it would be hard to go wrong with either one.
The Audya has Audio drums and guitars and as such sounds like a live band playing, even the non-audio styles and drums. The Korg sounds more live than Yamaha, somewhere in between.
Both have outstanding vocal harmonizers and processors. I think overall I prefer the Audya's, but it's a close call there.
I prefer the lead guitar sounds from the Audya. Most of the lead sounds are excellent on both. Yamaha, which is not really in this discussion, imo, has better lead sounds than either.
I prefer the Audya operating system, although the Korg Songbook feature is really great. Korg has touch screen but both have multiple buttons and switches, both fixed and programmable and are wonderful for live play.
I had zero problems with Audya. I have had one problem with Korg and I have been waiting for a part, under warranty, for almost three months.
In short, I am proud to have owned both of these wonderful arrangers. You can't go wrong with either choice, if you have a dealer who will stand behind you just in case of trouble. When I bought my Korg, neither Frank nor George had one and didn't know when they were coming. I needed to purchase before the end of the year, so I bought it from a reputable on line dealer at a great price, with 45-day return available. My problem developed after 7 months and the dealer said he tried but couldn't do anything except ask them to hurry. I guess that didn't work.
I have decided to sell the Korg out of spite. I know it is and will continue to be a top of the line arranger with all the features I need or want, but I'm old and stubborn so will move on, to a PSRS950 for now. Who knows what later, maybe Ketron, maybe nothing. The audience doesn't know the difference.
DonM