It depends what you will use the board for.

Are you using the rythms a lot to accompany singings ? If that is the case, then arranger such as Tyros is the way to go. Many of the forum members are one-man professional entertainers and they CANNOT stay in business without arranger keyboard.

BUT if you use it in a band with other people playing rythms(drums, bass, etc) then you want the MOTIF like keyboards that specializes in the SOUNDS. This is also the case for those people that composes songs and creates rythms from scratch (lots of work). Even a composer will benefit a lot from an arranger. I believe MOTIF calibre keyboards will beat the sounds of Tyros any day. But if you try to have a full band YOURSELF and accompany singers/your own, then MOTIF will fall short - it does not have arranger features.