We have gotten lucky and had mice, ASF's, and Rats give birth recently. The pet stores around here had a sale recently on ASF rats and they seem to always have them, but our opinion is.

Mice are a pain as they really don't like other mice in the cage when they pop and are nursing.

ASF does not seem too bad, but the babies are like as small as mice babies. Granted we got a female from the pet store with intentions of feeding it to a snake that was off food, and the snake still didn't take it. So we kept it and it dropped a litter of pups a couple days ago.

Rats lay the larger litters. "Most" ball pythons "can" handle a rat pup and very few ball pythons will ever get large enough to handle more than a medium to large rat. One of proper size and you are done. Rats are also social creatures so you can leave birthing moms together and swap in and out other females with little to no issues. Rats can also be held easily.