My LPS and Clams are prettiest under full light, so I voted mid day... but that's not the entire truth of the matter. My fishes, I like to watch them eat, and I do that under blue light, towards the end of the day. I enjoy looking at micro fauna, all the small critters that come out at night, which I do by flashlight. At night, in the main tank, or more commonly, mid day, in the refugeum (inverse lighting schedule).
Back when I had seahorses, the mated pairs would entwine their tails and parade around the tank together just after sunup each morning... that was very cool to watch.