No. 1 Donnie Freeman
The top NBA player that the Illinois basketball program produced has to go to Donnie Freeman. He is someone who had great numbers and even better accolades during his time in the professional ranks.
Coming out of Madison High School in Illinois, Freeman would join the Illini and would be one of the best college players in program history. He would average 20.1 points and 10.3 rebounds during his career in Champaign, and he was an All-Big Ten player.
After his time was done with the Illini, Freeman would head to the NBA. He was selected by the Philadelphia 76ers in the third round of the 1966 NBA Draft.
During his nine-year ABA/NBA career, Freeman would play for seven different franchises. He would finish his time in the professional ranks averaging 18.9 points, 3.5 rebounds, and 3.5 assists per game. His best season came with the Miami Floridians of the ABA where he would average 27.4 points, 5.1 rebounds, and 3.7 assists per game.
Freeman actually ended up spending all but one season in the ABA. He would make five All-Star appearances and was a four-time All-ABA player. He also made the ABA All-Time Team as one of the greatest players to ever come through the ABA. In 1973, Freeman would help bring home the ABA Championship with the Indiana Pacers.
The accolades and numbers for Freeman are impressive. He was one of the most prolific scorers in ABA history. I think Freeman goes down as having the best NBA/ABA career in Illinois basketball history.