If you have the mice, enough of them, and don't mind taking the time to give your snake a few mice each feeding (one after the other, never all at the same time), then go for it. Some swear that the nutritional value of rats is higher, but others have valid debates for that claim. More so, what I believe it comes down to, is simple convenience. One may have to feed two, three, or maybe 4 mice during a feeding as opposed to one rat. I feed rats, and it's easier for me. I don't breed any type of prey animals. If you're into breeding mice/rats, maybe it's not a big deal.

Honestly, whatever works for you. I think as long as your snake gets the volume of food it needs, it would be fine.