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If I was choosing, I would go with the JR Farm mouse mix. It has the small seeds and grains that mice love. I currently feed their dwarf hamster version to my dwarf hamster and he likes it, although I purchased four bags of it so it should last a while yet! The science selective mouse will be small biscuit shapes like the hamster version. These shouldn`t be sniffed at as they can be added as an extra to the JR mix, but only a few small biscuits a day to add variety. What I like about the science selective hamster one is that they can be softened for older or ill animals that may well be off their regular mix. So buying a bag is handy to have just for those times when you might need it. But I agree that I wouldn`t feed it solely on it`s own, even though it`s a complete diet.
The Beaphar I wouldn`t touch. I remember buying a bag of their Xtra vital food and the mice hated it! Rat Rations is well worth a look as they sell straits and other grains/grasses to consider. x