I wasn't impressed by the formating of the Sony classics. Some of the errors made reading difficult. I also had difficulty picking books from the odd selection of classics. I did find a few authors I wouldn't have read otherwise such as George MacDonald and Charlotte Yonge but after seeing the quality of the ebooks on this site, I wish I had gone through the hassle of the Sony classics.
What do you like to read? New releases? Fiction or non-fiction? What genres? Some of those answers can determine which free book sites or bookstores you may prefer.