I don't do any sub-zero backpacking, or haven't anyway. For above zero:
On the move, I like my Extremities windstopper gloves. They're usually good by themselves, but if it's especially cold, I'll wear an Ibex wool liner. If it's raining, I really like my Extremities Tough Mitts over the gloves.
For hanging in camp, I like my BPL VaprThrm mitts, with the Ibex liners if necessary. I also have a pair of the Black Rock down mitts, but haven't used them much.