Afternoon sex is rather nice, if you dont feel weird about doing it in the middle of the day or dont have to work.
Morning sex is just... well, lets put it this way. I like morning sex when its "brunch" sex because morning sex for me is just me waking up with the morning wood and thats just an annoyance to the girl.
Evening sex.... its nice. its nice for someting to tire you out, that if you have a girl that likes that after sex cuddle, it can go south fast if you are really tired and fall asleep after.
Honestly though, the best sex is voyeurism sex (or public sex, watever you want to call it) where you have sex in a public place, but dont want people to know. There's quite a few places I'll not mention a girl and I have defiled with 50-100+ people close enough to take notice and interrupt.