To kick things off we have illmatic by nas. At a time when rap was in its infancy the rhyme scheme was very basic and mostly focused on racial pride and rebellion, nas' illmatic album set the bar for the next stage of development for hip-hop. The song structures focused on deeper issues and the rhyme schemes were layered showing a different level of complexity and skill foor that time.
As a famous current artist best put it to describe how this album was at the next level for the times:
'I had that 'illmatic, on bootleg
shit was so ahead, thought we was all dead'
NY State of Mind