Thank you all who replied!
As I mentioned, I am interested in midi based (Tyros 2-3, 970 type) styles.
Yes, I agree that it is about "finding gems"... But I have a small private collection that was shared with me years ago with handpicked and not very common styles (of different genres), and many (about 30% were usable). But with large collections, I spent hours just to find a couple that "might" work. My problem (!) is that I like many different genres. So looking for a collection of newer styles made from scratch 2010 and later.
"Yamaha styles all sound very good". I disagree with this statement. They are good at their own time. I remember having PSR300 in early 1990s. That was great for that time for my uses. Loved QY70-100, again was great for its time and styles sounded "fresh" 20+ years ago. Not now.
----------Ok, seems no distinctive answer, I will try to change subject somewhat to what couple of people had mentioned.--
Speaking of assembling styles from available group... Absolutely good advice. Yes, I looked into it. And if you have a good suggestion past my list below, please let me know.
EMC styleworks - Overpriced, significantly outdated, clunky, non intuitive piece of software.
Yamaha Mobile Music Sequencer is the CLOSEST to desired workflow and very nicely done, BUT it is only for ipad/iphone not possible to upload generic styles and being on ipad makes it almost useless... Oh yes, it was not updated in years. If something like this was available for PC and would accept generic styles, I would be first in line.
vArranger being the king of soft arrangers dealing with midi based "styles" has potential, but unfortunately Dan stopped serious development past what it is done already, so I personally do not see style assembly on horizon.
StyleMagic YA came close, but again, way too outdated, developer (not user) centered, not intuitive, slow (probably of old code). One man show, already VERY slow development can stop anytime. USB license (instead of computer ID)
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If anyone has a suggestion of software that can remix parts of various styles to make a new styles which could be potentially better than what is mentioned above, please let me know.
Thank you.