Hip hop started off rhyming to 16 bars before Erik B and Rakim came along and broke up the technique with multi-syllable rhymes, which Biggie smoothed over.
Fast-forward to today…
Mos def makes lyrical poetry. Kendrick Lamar personalizes his raps with motives (re: short musical ideas) while MF Doom cleverly manipulates his bars with uneven phrasing and punchlines.
I'm surprised the video didn't include Nas so I inserted him below. Written at age 16, performed at 18: NAS “Live at the Barbeque.”