My first choice is Don M. He really touches my soul. None better at guitar emulation. Number two is Travel'in Easy. Again, it's the pure musical joy that comes out in their arrangements. The auto arranger is their number 1 tool in their Snap-On musical tool box. They both are experts at getting the most out of the technology that we all have at our disposal.
Dropping down to #3, I'm going to go with Martin Harris. I think he has almost single handedly shown off the power of the PSR - SX900-700 line. Genos too! He has managed to get me to invest in the Yamaha line of instruments many times.
Peter Baartmans is a wonderful demonstrator of auto arrangers but I sometimes get the feeling after listening to one of his demonstrations that I, a mere mortal, will never be able to achieve that level of musicianship. Still, I love hearing just what these amazing auto arrangers are capable of.
That being said, "May the fourth be with you".
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Musician's Theory of Relativity: E=Fb