The safe answer is Rakim.
The correct answer is Big Daddy Kane.
He was the complete package. He could do many styles, had the dance moves and the cameo cut, was the lyricist for the Juice Crew, and was behind Roxanne Shante's battle raps.
I love Rakim but he was not as versatile as BDK.
In high school the margins of my class notes were filled with Big Daddy Kane lyrics. I made diagrams showing the links between BDK - EPMD - Biz Markie. They were the holy trinity of rap.
Doug E Fresh, Dana Dane, the Jungle Brothers, De La Soul and others were there too; but as planets around the rap stars.
I am still not sure how I found this music as a suburban kid. It all came as tapes from my friend Tom. They were the primer that led us listening to Marly Marl's The Symphony over and over in Matt's basement while we played ping-pong.
But Big Daddy Kane was always the one I listened to the most. Even in graduate school I was writing his lyrics on chalkboards when I was board.
When my wife was just my girlfriend I gave her a few quizzes, one test was on a drive from southwest Ohio to northern Michigan. Much of that drive was spent listening to Big Daddy Kane tapes. Had she complained our history would have been history. Rather she complimented his ability to work the phrase "party people" into just about every song.
His line that gets stuck in my head most often is "So pick a B.C. date because you're history".
And the song I listened to most often? Many nights were spent in the '87 Accord with 'On The Move' turned up all the way as I drove from Matt's and past Jill's on the way home.
Without Big Daddy Kane there would be no Jay-Z. Maybe not even a Paul Barman (which would probably make many people happy). But to my ears there is direct link from Big Daddy Kane's compound syllable rhyming (e.g., "the best oh yes I guess suggest the rest should fess/ Don’t mess or test your highness/ Unless you just address with best finesse/ And bless the paragraph I manifest") to today's MC Paul Barman incredibly clever quattro-syllabic to mono-syllabic rhyming. (e,g., "That sure made it sat-ur-at-ed")
What sent me on this sentimental journey was a post at Herohill that linked to a documentary about Big Daddy Kane.
Watch it then see the 2005 VH1 Hip Honors celebrating Big Daddy Kane.
PEACE