Wow, really nice thumbnails. In all of them, you've manages to show a good chunk of all three sides of your character, which seems like it wouldn't be easy. Nice work!
As for the designs you posted, my only comment would be to avoid some of the more complicated headpeices. You've got enough work just conveying all three sides clearly without making intricate helms that make them harder to read. I would think that simpler, more distinct shapes would help the peice's clarity more.
Good luck whichever you choose!