as DonM has just said, its down to your needs. the keyboards are great, all 3 are really good to own. there have been endless discussions about these keyboards and more. the favourite has been the X1 in which the PSR9000 has been close if not at least as equal to its popularity. I have a personal preference, and its the X1. But i have my reason for this. I recommend you listen to them if you can, as you said already they are expensive and require care when chosing.
some people have owned X1s and changed to PSR9000 because of its user friendliness not being all that. Some people have tried the PSR9000 and said it was quite similar to the PSR8000. There are many views. For what I use the keyboards for (which is occasional gigging with my father but i mainly want good styles for my songs i play/create), i chose the X1, for me it has the best styles together with excellent sounds. The PSR9000 has many advantages also. its a tough choice if you are a neutral.
i hope this helps.
Tyros4, PSR-SX900, PSR-S975, Pa-1000, & GEM WK8 SE Megastation