Questionable shapes. It looks like it's broken a few knuckles.
They're out of place.
Hands are difficult. Study hands before attempting to draw them, the result will be better than if you just improvise. If you have trouble finding a certain pose/position, look at your own hand and/or take a picture of it. You could also ask someone else to help you with it.
The first drawing is really sketchy and needs a tad more detail here and there. The thickness of the fingers is also wrong. They go from thin to thick. That really gives it an unrealistic look; avoid it.
The wrist is turned awfully much in the second drawing. Besides, the fingers look awkward. Pointy and incorrect shape.
Now, the third one is, compared to your others, pretty decent! Although the pinky finger is just a little too long. And the thumb looks like it's had surgery.
The fourth one also has questionable shapes here and there. The thumb's knuckle looks really awkward; as if it was broken or displaced. The rest is a little sketchy. But the thickness of the fingers is obviously better than your other ones.
Overall, you need to practice. And like I said, hands are difficult.