Its an Arranger. You buy it for Arrangements and styles. Yamaha has the most support in that regard. Thousands of styles available.
Voices are subjective, editing is easy if you know whatever keyboard one is using.
The Tyros is the Best, the most supported,has fanatical customer support, the most available, has an expandable voice set, Up to date re memory schemes USB 2, ATA off the shelf drive (apparently any size as a friend just dropped a $55 160Gig notebook drive in his T2 and it sees all of it), and has the most Styles available which I believe is the most important thing in an Arranger...Support, technical. customer, and software. Yamaha is Everywhere as well. Any Yamaha Piano or MI dealer can help you.
Disclaimer. I sell the Yamaha and Korg and have no experience with Roland's G70 and Ketron sounds good but local support is hard to find so I did not consider it. I owned a PA2x and sold it and bought the T3. Its a keeper. I use it solely for song writing via a DAW.
[This message has been edited by Kingfrog (edited 01-31-2009).]
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Yamaha Tyros 4
Yamaha Motif XS8
Roland RD700
Casio PX-330
Martin DC Aura
Breedlove ATlas Solo
Bose MOD II PA