Yves,
Welcome to the forum. All these keyboards have been compared and discussed many times.
If you will go back through the postings on Chris' previous Arranger Keyboard Forum, you will find pages of such discussions.
There is a link to it on Synthzone BBS page. You can no longer post there, so after you read all this, if you have more questions, someone here will be happy to help.
I think you will eventually come down to choosing between the X1 and the PSR9000, but that's for you to decide.
Don