First of all, the lines on the bodies of both sprites look just plain wrong.
Jin:
Hair from MV just doesn't fit the style you're at.
The legs looks funny, especially the lower parts.
And it also looks like he has two left feet.
Kuwabara:
I am not sure, but his arm looks uncomfortable and short.
Hair could be a tad bigger and face longer.
The darkest shade of his pants you used for folds also stands out.
And I like the first color more.
That's pretty much it for me and sorry for the late reply.