There are a lot of great albums being mentioned here. But I would define the best debut album as being the debut album containing the most songs I've heard on the radio at least 10 times in my life. Using that yardstick, the only album that comes to mind is the debut album from Boston. I have heard EVERY single song on that album in heavy rotation on the radio for decades. I can't give rightly give that title to any other debut album, as no other has really even come close to matching that feat.