I really like the predator camo OPT series jacket and pants, with midweight or expedition weight wool base layers from Minus33, wool beanie, wool socks, and fleece face mask. I feel more mobile in this kit, than in full insulated bibs. I also find it easier to draw my bow, because the clothing is flexible. The predator camo OPT jacket and pants are wind proof, too. I've been in 30-40 degree weather with the kit above and was warm. I'll also agree with Sheridan that an insulated one piece suit is probably the warmest.

Also, I'm a big fan of the predator camo OPT line. It's well built, quiet, comfortable, and I really like the camo pattern. It blends well with the western Oklahoma terrain.