I've seen License to Ill and Check Your Head mentioned but the best and most influential of all BBoy's albums was actually Paul's Boutique. It set the stage for what BBoys were to become which was a hell of a lot more than party rap. If you're a fan of BBoys I HIGHLY SUGGEST you listen to public radio KEXP Seatle's retrospective on the album. They played every song that was sampled and went into some deep discussions regarding the band and the "new" direction. I was so impressed that I donated. The show is several hours long but believe me time will fly when you listen to it:
http://blog.kexp.org/kexp-steps-inside-pauls-boutique-on-friday-july-24/