Using Bakhtin's concept of genre (1982), this article presents a quantitative analysis of the most popular genres among the productions of Spanish-speaking BookTubers (Book + YouTubers). Its aim is to determine which discourses are the most dominant discursive forms in their production and the repercussions these audiovisual genres have on their audiences through quantitative indicators of popularity (views, likes/dislikes/comments). We quantify the presence of audiovisual genres in a random sample of videos published in 2017 (n=368) using digital methods, through the informatic script YouTube Data Tools to obtain information about the videos (Title, Description, Number of Views, Comments, Likes and Dislikes). Evidence shows that BookTubers are able to use a great variety of audiovisual genres that come both from other YouTubers (such as vlogs, challenges, hangouts, hauls or unboxings) and from other media (reviews, rankings, lists, interviews). The most prominent in our corpus are the review, the list and the wrap-up, which fit a traditional recommendation function; however, the most popular among their audiences, in terms of views, comments and likes, are those in which the BookTuber performs a thematic selection of several books, such as lists, rankings or wrap-ups. This reinforces the curatorial value of their work as reading mediators.