The nutritional benefits are slightly better with rats, but the real reason to feed rats is because as your BP grows so will the size of the rodents required to feed it. Mice only get so big so if you are feeding mice you will have to start feeding multiple mice at a time, this can be very expensive and time consuming.

Do you know how much your BP weighs? (preferably in grams)

Weight is another good way to determine prey size, a young BP should eat rodents that are 15% of the BP's body weight.

so a 100 gram Bp should get a 15 gram rodent. (100 grams x 0.15 = 15 grams)