Love the bottom one
The swinging arm thing doesn't seem right. If there's no force applied from the source (like a dog wagging its tail) then the weight of its end tip should control the swinging. So that means the fall, or the start of the swing, should be much less abrupt. Dunno if that explanation makes sense? I can try an edit later.
If I'm reading it right, it is a study of one of the examples from the Animator's Survival Kit and supposed to be the arm of a person in an exaggerated stroll. If it is that, it still looks a bit odd and unnatural, not flowing too well. Must be the t...t...t...timing or the sp..sp..sp..spacing.