I currently go with Big Cheese Rodents. Packaged nicely on trays for easy stacking in the freezer. They also have the best prices right now.
I also like Layne Labs for rodents. They are not packaged on a tray but they are frozen and then bagged.
On the other hand, I was not thrilled with Rodent Pro. While my ball pythons didn't care, packaging was a turn off for me. In comparison to Big Cheese or Layne Labs, Rodent Pro throws the rodents in a bag and then freezes the bag. I had flattened rodents, folded in half rodents, and rodents that were frozen so intertwined I had legs or tails break off. I know some people don't care about that since they are going to be eaten anyway. I, for one, found the left over, broken off, rat body parts at the bottom of the bag kind of a question mark.