There were many options for me to consider: TumbleBooks, PebbleGo, Scholastic Storia, and so on. Somehow (probably through Scholastic marketing) I found out about Scholastic Bookflix. The program pairs nonfiction and fiction digital books for grades Pre-K-3. They are themed by subject matter, including animals, holidays, biographies, and so on.
The fiction books are the Weston Woods video adaptations. I hesitated with the idea of this at first, but didn't let it bother me for too long realizing the videos include the text. I also took into consideration all the nonfiction that came with the program. The nonfiction is in an eBook format, but the reader has an option of having it read aloud. So many valuable topics offered as pairs!
My school began with a free trial version for 3 months. Even before this trial ended, I had one of the 2nd grade teachers tell me how much she enjoyed the program and uses it a lot with her students. A 1st grade teacher told me how well the program even worked with the reading curriculum because there were matching digital books that the students could view in addition to reading them in their readers.
The program is a bit pricey, but I used Scholastic Dollars to reduce the price. The whole school had access to this site, either by link or with username and password -- this made it easier for me to share with my students and their families. I will definitely be renewing my school's BookFlix subscription.