MSNBC. Ever since Olbermann got fired after 2010, the music, graphics and discussion roundtables with Maddow as the main newscaster, the station has gotten a lot better for Election Night. It's fun to see O'Donnell's or Hayes's views on results as they're coming in, plus they have a whole bunch of people stationed at the main camps for the night (Grimes, Orman, Perdue, Gardner, Burke etc.). You can't have an election without Chuck Todd's maps, either.
When 7:30 pm EST rolls along though, I'll probably be watching the local news network for Ohio down-ballot results for a short awhile (since MSNBC will only call OH-Gov for Kasich/post Ohio U.S. House races at the bottom of the screen and be finished on Ohio for the night).