I prefer the turkey-sheep armatar, now that I see minecraftsniper's armatar at a larger scale. The mouth and the eye look like someone pasted them on there without really taking the time to blend them so they look like an actual creature. The turkey one seems consistent enough so that it would at least scale up well.
Both are very good armatars. I'll pick the screaming monkey because it is easily recognizable at a very small size. The sheep turkey is better piece of artwork though.
Normally I'd choose the flaming ball of fur death, but the turkey sheep thing reminds me of John, who should really get tired with Kong about now and come back.