Let's face it, all the current arrangers sound great. Korg should get even better with the new piano and guitar voices.
What is most important to me are the little things that make performing easier.
Thanks I like about Korg PA3X:
Many programmable sliders and buttons.
Excellent touch screen.
Easy access to one-touch buttons even when the screen is displaying lyrics or something else.
Excellent mic processing and vocal harmony. But everyone knows this.
Ability to use light-weight, inexpensive 5-button foot controller.
Touch strip!
Joy stick!
Very manageable size and weight, especially compared to Tyros and Ketron.
Easy access to third party sounds, drum kits, etc.
Wonderful Songbook which stores everything you want or need, in any order or by most any criteria--genre, user lists, etc. You can apply custom numbers to each entry if you wish, for instant recall.
You can plug cables in while seated because the ports are labeled on TOP of the keyboard. Don't have to lift it up and look at the back! Yes, it's a small thing, but saves time and effort.
Internal power supply with standard cord.
You can edit and save things while you are playing. You don't have to stop the style or song to quickly change something, maybe change a voice, volume, mute, etc., and save it.
There are dedicated buttons and knobs for vocal and harmony controls, and lights to show you when VH is engaged and mic is on.
There is an easy-to-use LOCK system that lets you save those items that you don't ever want anything to change, perhaps fingering mode, split point, VH settings, pedal assignments and much more.
You can elect to have the style and/or sound and performance screen automatically close, or if you prefer, stay open until you close them.
You can totally edit, remove, replace, rename, move any FACTORY styles you want. If you don't do modern DANCE, take them out if you wish. Put all Willie Nelson styles there instead.
You can always restore them if you want.
Despite common misconception, there are tons of additional styles available free, and Korg periodically does free updates with new styles and/or sounds!
If you are into using midi files and/or MP3s, there is a dual sequence player that allows you to have two songs loaded and fade between them if you wish. Of course all this can be saved to a Songbook entry.
There are a few of the things that you don't see in a demo. You have to play the arranger for a good amount of time to determine what is important to you and your style of playing.
Regarding the PA4X specifically, some of the new features are the ability to save Chord Sequencer to Songbook entries. This is BIG. Also it now FINALLY allows direct play from USB device. Loading to audition is no longer necessary! Touch screen is bigger than 3x.
I'm sure there are quite a few other improvements but these alone are enough for me to give it strong consideration.
For sure there are things to love about all the arrangers. I love the Ketron live sound. I love the size and weight of PSRS series. Love the guitar sounds too, although the others seem to be catching up. Love Casio piano and organ sounds. Love BK9 organs, weight, styles and...well that's about it for that one.
Sorry for rambling.