I use to think one arranger might be better for this type, that type, etc....but I believe, like Donny said, it's the player that can make ANY pro arranger do any type music you want. They really all have the tools to do so. It's what you find the best to work with.

With that said, I do like the Korg for the harmonizer funtion. It adds a special element without outside gear. Roland has one also. Yamaha might be less attractive in that area, although MY OPINION ONLY.