For sheer features, sounds, upgradeability, and build quality the Wersi Abacus is by far the best arranger keyboard available today but its quite cost prohibitive ($7,000+ USD).

In the price range of under $3500 arranger keyboards I feel the KN7000 has no competiton. Given the fact the KN7000 can be had for much less than $2700 via mail order, its a real bargain.

Yamaha's Tyros is also very good but the sounds to me don't seem as realistic as those on the KN7000 and the Technics sequencer is amazing. Yamaha's sequencer on the other hand is quite poor.