Yeah, looks like the KALLAX is preferred, the BILLY does leave a bit of album hanging out. (Although I don't believe you need all of 13" for an album sleeve—perhaps closer to 12½". Still overhang though.)

There's a version of Billy that is deeper (39cm = 15.35in), but maybe only in some regions: https://www.ikea.com/gb/en/p/billy-bookcase-white-90401932/