Lyrically, The Black Album might be Jays best. It spawned a lot of the quotes and catchphrases that people associate with Jay, chopping his voice on the hook etc.
Not to mention, all of the remixes of that album were influential on the careers of A LOT of up-n-comers
Of course, RD and BP1 are the other 2.
American Gangster had a lil concept and throwback sound, but lyrically, he was still doing the soft, whiny thing from Kingdom Come on most tracks, and just using the concept as creative license to blatantly brag about hustling again