The name of the thread sounds confusing as hell. whose influence greater than their music? So Pac is basically that rapper, because he was more than just a rapper.
Now since you say "who don't have the greatest catalogues", pac is no longer in that conversatiom, does that mean we talmbout rappers who birthed different styles and shyt while not having classic albums? Because then it denies the question that you asked in the thread's name. Influencing someone elses style is the part of your music.
Anyway, I'll mention immortal technique. His catalogue is very mediocre, his rapping is boring as hell, he sounds like he is reading over a beat rather than rapping. But he is known for adressing social issues and stuff, if some tv show or some channel invites him to talk, he always talks about social stuff rather than his music, so here we go.