While the pups are on the floor, gently restrain them one at a time by putting your hands on their shoulders, and gently pressing down. Also, if a pup lies down, put your hand over its shoulders and gently press. This is a dominance position, and shows whether the pup will accept your leadership readily. If it tends to complain and move out from under your hand whenever you try to restrain it, it could be a rather willful dog, and may be challenging to train. Pay attention to the pup or pups that keep coming readily to you, and that seem to choose you.
Animals are often fairly clear about who they like.
If this is a pup who comes readily to you, that allows you to gently restrain it, that plays happily without become ferocious, that is not obsessed with human hands and clothing, then you will likely have a good-natured dog that will be a joy to own. Make sure he's housebroken. See if he settles down outside his cage area or if he continues to be a bundle of high energy. Decide what energy level you can handle in a dog. If he does not tolerate this or actually snaps at you, cross him off the list.