Koenigsegg Agera R rear calipers are at 3 & 9 o'clock behind the axle. Their engineering is probably some of the more current and advanced.
Porche's Carrara GT had the rear calipers slightly lower than 3 & 9 o'clock in front of the axle.
Then you'll see some F1 cars with bottom mounted calipers.
What is best and how much influence does it have relative to the desired performance objective?