Both WDEL and WILM offered wall to wall coverage. Both stations had guests to discuss the issues, and live reports, victory/concession speeches, etc, from various places around the state. WDEL used CBS radio for the national info, WILM used Fox News Radio for their national coverage. I listened back and forth to both. Both were fine.
Didn't tune in to Channel 12 so don't know if they offered any in depth coverage of Delaware's races. They usually put more emphasis on PA and NJ races, same with WHYY-FM.