Diamond has released the top 50 for May, Marvel took the top Comics spot with X-Men #1 and holds 6 of the top 10. Batman & Justice League help DC hold onto the remaining 4 slots in the top 10. Walking Dead #110 comes in at #13, the highest ranked of the non Marvel/DC books.
Boom! grabs the top Graphic Novel slot with the Adventure Time OGN Playing With Fire, and also slot #5 with the Adventure Time tie-in Marceline & the Scream Queens.
For more, check out the Diamond web-site: