I've been thinking about this for a few days myself, reading the comments from the others here to consider their opinions, etc. In the end I had to vote for myself.
I went with Bilbo's. Though I'm not so sure about the blue, the overall color application and finish gives a very impressive and realistic looking model. The skulls are nicely textured, the facial detail is just enough to look alive without the over-obvious eyes and features, shading is great.
Troll King: a very close second. I had to knock these two around a lot in my head. I can’t even tell you exactly what moved me one direction or the other. I’m not a huge fan of GW’s Orc Shaman models so maybe that was part of it, but I believe this (and Chris GoM’s) stand apart from that prejudice. Whatever it was I can’t articulate it more than just saying it was the feeling I had to go with.
Chris GoM: The pose is great and the color selection and application look very natural to my eyes. The decision point really came from the mold lines on the Warg I’m afraid. Maybe it’s just the pic but the line across the face and tail still appear prominent. Other than that I really love it. A little better of lighting on the model for the pic may have helped some more (I was suffering from this too). Also, I know the base doesn’t count in the selection, but I think at a subconscious level it probably does impact us each somewhat. Especially on a mounted model where so much base is visible having a little more detail would help the base be less of a distraction (my eyes do drop down to the base sand somewhat).
Wah Wing: The Uruk shaman is one of the few shaman models I really like and I think you did a great job capturing a natural look and feel on it. It was in my top three and I bet it looks amazing in your army if you used a similar color scheme for all your Uruks.
Chris – still one of the best examples of snow I’ve seen on a small model.
basshead: The entry is a great example of highly detailed painting and the base shows off what really can be done for a small model.
GtW: I would love to see updated pics of yours if you get a chance. Really creative idea and it appears to be well built. A very complex conversion indeed and it looks like you did a good job with it. I don’t think your pics do it justice. I’d love to hear how you plan on playing it as well if you’re going to incorporate it into the game (what would it be a proxy for, for example, or will you somehow incorporate it into a standard formation).
Just because I didn’t call out the others specifically does not mean they were any less impressive in their own ways. Mostly just don’t want to appear too wordy and also I’m posting from work…don’t tell anyone.