There are some with superb detail (high polygon count, high resolution textures), like the Proto-Drake Whelp, and others that look really horrible, mostly wow classic critters, like the Alpine Hare.
Which one do you think stands out the most, if polygon count and texture resolution are the two things that matter?
I'm with the Proto-Drake Whelp for now, it's basically a shrinked down Razorscale (Ulduar Instance Boss).
(Can't play WoW right now, so I make interesting threads ^^)