I would choose the kitten who appeals to you and who seems to most friendly to you. Please don't take the kittens away from mother for several more weeks. The kittens still have much to learn from mother cat and littermates.
Remember also that mother cat can get pregnant while still nursing her kittens. Assuming this was not an intentional breeding, I would take her to be spayed asap, not while she's in heat, however. So many thousands of cats and kittens are put down every week because there is such an overabundance of kittens-especially those offerered "free to a good home." I hope your kittens get excellent homes.