Since I have been in Chicago around 10 years ago in college, I can only think of more recent.
I say the B 96 Street Mix, 12 o' clock Lunch Party, and 5 o' clock Traffic Jams back in the Party Radio days. It was creative, unique and it seemed like the mixers especially on the Street Mix had fun doing it.
A close second was Terry Foxx back in the day from 2-6 pm on B 96. I think no matter what music was played during that time, everyone who was not even a fan of the format listened to him. He was just very personable and good with his audience! He was always #1 or #2 in his timeslot.
Third was the B 96 Street Flava' that played the club cuts not heard everyday along with mixes every hour. A Sunday evening was not completed unless you listened to the Street Flava'.
"This is the B 96 Street Flava'. Party Radio B 96. B 96 has got the flava (x3), the what? The street flava' for yo ear!"