I know that my response is somewhat late, considering that this original thread was started in January 2021, but I thought that I would respond anyway.
I have used arrangers since the Mid-90's, in one form or another...
My first 'arranger' was a Technics SX-PR270. It was called a 'Digital Ensemble' and cost me about $5k USD. I wrote many albums on that thing and took it live (with the help of bandmates, since it weighed about 200 pounds). It had 32-notes of polyphony, a 100 watt stereo speaker system built in, and 88 weighted keys. It was one of the best units I have ever owned. I lugged that thing everywhere and it always performed well.
I lost it in a bad business deal (lost a bunch of PA gear too) and there are times that I still miss it. Its ease of use and sound really drew me to it.
I was also exposed to the Solton (Ketron) arrangers in the late 90's and they had a fantastic sound. Additionally, a mentor/friend of mine had the Korg i2 and we always had fun jamming together. I had switched to full synths by that time, and was firmly planted in the Ensoniq camp by then...
My next foray into arrangers was with the Roland E-09. I needed something quick and dirty that I could use as the principle music instrument for a band I was leading. I was able to MIDI a bunch of gear to it and made my sound huge. I was the band, providing all of the instruments for the singer(s) to sing over. I used it on the road for years and when I started my nursing home music ministry, it was the exclusive instrument I used at the homes. It had all of the styles I wanted, a good Roland piano sound, and a speaker system that did not mind being turned up all the way to minimize my having to bring external speakers to the homes.
Sometime during 2012, I ended up purchasing the Korg PA500. It was vastly different than the E-09 and I just did not connect with it, even though it sounded really good. I ended up getting rid of it and went back to the Roland E-09.
Fast forward to 2017 and I decided to get another arranger because the E-09 started sounding dated. I had actually bought another E-09 as a backup to the first unit, as I was playing around 80 nursing homes a month, I had the direct line to Roland, because I kept ordering extra buttons for the E-09 and was replacing them myself fairly often. I even had to replace the LCD screens in both units. I still have one of those E-09 arrangers in a case in the closet...
In September 2017, I bought the Korg PA700 and never looked back. I waited a few months before actually taking it out to the nursing homes, but once I did, it really opened up what I was able to do at the homes. The PA700 has turned into my main songwriting tool in the studio, still does the nursing home stuff, but is also the principle instrument for any duo/trio that I am in. I also use it for my solo music and it works very well.
I had considered the Ketron products as well, but support here in the USA is limited, as are available units to play. If I am going to spend that kind of money on the Audya or SD9, I really want to play it first before pulling the trigger. I am intrigued by the tech in the Ketron products, as I think that their live-backing stuff is really realistic sounding. I know that Yamaha has dabbled into using WAV files for guitar stuff and such, but Ketron really has a neat sound and I like how they sound.
The biggest limitation with most arrangers are the guitar sounds, especially when doing rock music. It is much different to use actual guitar riffs via WAV or whatever than to use a guitar sample and run that through an amp simulator. I like the live drums too that Ketron used, and the bass sounds. It is like having a real band in the box and you just put them together.
Even though the Korg PA700 does not do what the Ketron does with the backing sounds, I can still get good tones from it and my PA700 can rock with the best of them, in my opinion. The DNC stuff that Korg uses really helps with creating realism in the sounds.
I have experience with Yamaha arrangers too, but I always thought their sound was very canned and almost bland sounding compared to what I am using. Maybe it would be different if I had a Genos, but I do not think so. I have had friends who had Tyros arrangers and they LOVED them and their integration when producing commercials, jingles, etc...
If I had the $$ and availability of a Ketron product in my area, I would probably own one of those, maybe even instead of the PA700. With that said, I do not regret the purchase of the PA700 at all, and it has totally paid for itself many times over since I have owned it.
I am not experienced with Wersi, Orla or the other offerings out there from less well-known companies here in the states. I did own a Roland BK5 for a time, but when compared to the PA700, I ended up getting rid of the BK5, as it was too far underneath the feature set that I needed. I got spoiled by the touch screen of the PA700.
Some users in the Korg forum have complained about the feel of the keys on the PA700 and other Korg arrangers, and I guess I am a different type of user. Sure, the feel of a nice weighted keybed is preferred, but I can adapt to any keybed and play on them. Maybe it is all of my years on the road playing so many different synths, but I am not terribly picky. I do prefer a nicely weighted 88-key action for solo piano, but other than that, I guess I do not mind all that much.
With the above said about action, my favorite action is on my Lowrey (Kawai) digitla piano. It is so solid and just feels like butter under my fingers. I also have a couple of Korg Kross 88 synths and the action is good on those too, especially live. I also recently bought the Kurzweil SP1 and while the piano sounds on it are absolute crap, I LOVE the action on it. I also love the action on my trusty Ensoniq VFX-SD, but it is over 30 years old and well-worn. I do not mind the action on the PA700, M50, or Kross 61 units I have as well, but I would prefer to play the 88-key units, especially for piano. Again though, I am not terribly picky.
One of the worst actions I have played on was on the Roland VR-09. Since I was using it for Organ sounds, the lack of waterfall keys made really digging into the organ technique kind of difficult. I have a background with organ as well, and those waterfall keys really do help with organ technique.
Maybe I got off course a bit? Not sure. Even though I have a lot of stuff from the 'Big Three' companies, I also like products from the 'underdogs' because it seems like they have to try a bit harder...
Grace,
Harry