I just finished another comparison of Sony vs. Amazon for ebooks using dugbug's SF/Fantasy award winners spreadsheet. From the 437 titles in the spreadsheet, Amazon has 133 of them (30.4%) and Sony has 98 of them (22.4%). Amazon had 37 titles that Sony did not. Sony had 2 titles that Amazon did not. Details in post #64 here:
https://www.mobileread.com/forums/showthread.php?t=24766