I've used a merino buff for a couple of years now in a variety of conditions both for cycling and hill walking. Buffs make great scarfs which can be pulled up over your face to give protection against the wind. Used this way, they're thin enough to let you breath through and so they're pretty comfortable. The merino version is expensive, but lovely! Compared to a normal buff I think they're warmer and more comfortable to wear. They also have the smell reduction capacity of all merino products. A normal buff does the job though, so if you're on a tight budget you'll not go wrong by buying the cheaper version.
In terms of performance, a buff (or 2) is enough for me, but if you go out in brutal conditions (-10 with 60mph gusts say), they'll not give you enough protection and a sexy full face balaclava would suit you better....