The Natural Ninja
I recently picked up the Zissou version of this and it is awesome. The first night I had it, I slept in it, to test its warmth out. Two thumbs up. Not only does this Ninja suit have all the great features of the normal Ninja, but it is also made with Merino wool. Merino wool smells better, and keeps you drier. I also like the idea of having a natural fiber against my skin. Just saying.
Fit wise, I am 5'11", 160lbs. I found the M to be an athletic fit, while the L was a comfy fit. I went with L, even though it was slightly loose. All depends on your preference.
On top of all that, the Zissou tribute is great!