Several options :

1) buy another Tyros 5, still the best
2) buy the new Yamaha Montage and add Varranger or a Ketron MidJ pro
3) buy a Kronos and add a Ketron Midj Pro
4) buy a PA4x, its the only arranger that comes close to Tyros 5
5) Ketron SD7 might also be an option if you really like the Ketron styles ( midj pro would give the same style quallity)
6) Roland.... i would wayt till after NAmm to make a decision on that... as said the BK9 is a valid option..
7) Casio MZ-X, who knows how godly it might sound, wayt till we have seen demo's after Namm


In genreal chances are huge anything but option 1 will feel like a step back...