I think the troll is good - it feels cleaner than the others because it has larger areas (clusters in the local parlance) of colour, whereas the others feel a bit noisy.
I tried an edit of your player sprite to address a couple of things
1) Weak pose - with his feet together like that, he looks scared - or like he needs the toilet

Also, his sword arm feels too far out.
2) Cleaned up messy pixels, and simplified things a bit to try and make it more readable.
3) Mostly removed the internal black outlines - at this size, they start taking a lot of space, and can make things kind of flat-looking.

I'm not sure what you should do with the face though - the light coloured eyes contribute to the impression that he's terrified (eyes open too wide so we see a lot of the whites).
I couldn't manage to do any better with so little space, so I tried just putting it into shadow. Not sure if that makes him look less like a player character though. Maybe you could try giving him a less full helmet?
Oh, and why does he have bare hands if he's wearing full armour
