Haven't done one of these in a while. Might as well switch up the genre.
Bring up the name Rakim, and the short term response you'll likely get is "Greatest rapper ever." He can take a phrase that's rarely heard, flip it, now its a daily word. Sometimes I think to myself that I'm wasting my time bothering with hip-hop music. When that happens, I put on one of his tracks, and everything makes sense again.
A common praise for Rakim was that when he dropped in 86-87, MC's were rhyming simple words like "rat" and "cat." Rakim took that and made it a fuckload more complicated (i.e. Minute Maid & Renegade). Sometimes he would come close to making two exact verses rhyme!
Rakim sadly does not have the popularity of other fellow MC's such as 2pac or Biggie, but that's because those two are dead.

Seriously, for whatever reason, Rakim just never managed to craft a pop-song that was etched in the minds of the masses* like "Gin & Juice." He also doesn't exactly have the catchiest music in hip-hop either. But that's not what he's about, and Rakim knows that's not what he's about. He's about the rhyme, and the rhyme gets rougher as the rhyme goes on.
*Incidentally, you know that "Pump up the volume" line you constantly hear in 90's dance music? That's a Rakim sample from the song I Know You Got Soul: "And you sit by the radio hand on the dial soon, As you hear it pump up the volume "
Best album: Don't Sweat The Technique
Best songs: I Ain't No Joke, In The Ghetto, I Know You Go Soul, Casualties Of War,