In all the studies (and reviews of studies) I’ve seen on meditation, I’ve never seen anything scientific about best time of day to meditate. Maybe it exists, but I’ve never heard of it.
From the standpoint of a long-time meditator, plus someone who teaches meditation, my practical answer is this: the best time to meditate . . . is whatever time you will actually do it. It’s a variation on the old line that the best exercise in the world for you is whatever you will actually do.
This said, there is science that the mind is quieter for most people when we first awaken in the morning, plus we are less likely to fall back asleep, so that is an easier time to meditate. Additionally, meditating in the morning lays a good foundation for your outlook and mood for the whole day. (And as a practical matter, if you meditate before the kids get up, if you have any, the house is still quiet.)
Science also shows that just before sleep, the mind and brain are very receptive. In this hypnagogic state, the influence of meditation is going to be high, with results that could ripple through the night. The tradeoff is that we are less alert since we are sleepy.
So perhaps the perfect combination is have your main meditation in the morning (however long it is, even just a few minutes), with a minute or more just before sleep.
But remember, no matter what the scientists say, the best time to meditate is the time that works best for you.