I would like to echo everything Danny has been telling you. My opinion is also based on my experience with all the keyboards you are mentioning. I sell the X1, the WK8, the PSR9000 and also the Korg i30 and the Roland EM2000 which are also in the catagory of the others. All these keyboards are very good, but as Danny has stated, the styles in the X1 are just plain great!.. All the others sound more keyboard like, but the X1 sounds more like a real live band. You might like some sounds in other keyboards better, and that would be your choice to make, but the styles are what sell the X1. Also, as Danny has suggested, turn off or go to the arranger function button where you can not only turn off any of the many style tracks you don't want to hear or change the instruments to any sound you want and store them in the style/custom locations (200 of these may be stored).
I have played and played the PSR9000 and PSR740 styles for hours and hours in my store, and as I have posted on this forum before, these styles still sound like all the Yamaha keyboards have for the past several years. There is nothing wrong with this, and for many players it is exactly what they want, but I am always listening for something fresh and new and especially authentic sounding for certain styles, and my opinion is that the X1 has not been matched by anyone to this date. I really hope someone else does soon, because this is what drives our market and makes it more and more exciting to be a musician in these fast changing times.
To comment on the WK8 for a moment, you will find that it's interface is very confusing for the first time to generalmusic users. There are many buttons to push in order to change a sound, and if you are not careful, you find that when you think you are changing lets say an upper 1 sound, you are in the upper 2 sound instead, and so you are changing the wrong sound. This is a very common mistake made on the WK series of keyboards. The styles are very good and the sounds are good, but not great. This is a keyboard designed in 1996 by generalmusic (the WK4) and has been around a pretty long time. Generally, we see changes made every 2 -3 years in our industry. There are things I would really like to see improved on the WK line. The most important being the ability to play songs directly off the floppy or hard drive without having to wait to load. This is the only keyboard in it's catagory that can't play direct from disk. In a live application this takes to long if you are playing a song and your audience calls out for another. In all other keyboards it only takes a matter of seconds to find another, and in the case of the Solton X1, you can be playing a song and finding another while still playing the first. Also in Solton, you can be playing a song on the keyboard using a style, and if you select single Registration mode, and have made hundreds or thousands of different registrations and saved them in a folder on your hardrive, you could call up any of these registrations while playing another, and at the beginning of the next measure you would have your new registration. Most of my customers are now using this feature when playing live, but never knew this feature even existed until I explained it to them.
I hope you make a wise choice and I agree with Danny that you give any keyboard you try a fair chance.
George Kaye
Kaye's Music Scene
Reseda, California