Mid-day. Better would be late morning. It allows me to have a relaxing, un-rushed morning; I can pack that day instead of the night before; and the L.A. traffic is light for my drive to the airport.
I like to fly around mid-day, so I can get up at the normal time and take my sweet time getting ready and checking in.
I live CA. If I am flying to the east coast or Europe, I take the red eye. When I’m flying home, I take a mid-morning flight.
I’m the opposite - I’d much rather arrive at night, because any time I get off a flight more than five hours long, I am ready to collapse.
Although upon reflection, late morning/early afternoon flights mean I don’t have to worry about traffic jams on the way to the airport.