Since you asked
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I think what you may be interested in may not necessarily be an arranger keyboard. Arrangers have built-in automatic backing tracks that follow your chords in real time.
If this is what you need, you've come to the right place. Also there are quite a few here who do use workstations that are not arrangers.
Most any of the top-of-line arrangers would work for you most likely, but I would pay particular attention to the new Korg PAX, GEM , Yamaha Tyros, Ketron SD1 or the as-yet released new Roland G70. They all have excellent sounds and have proven reliable.
Some of the Young Coots will have to address the workstations!
DonM