I've never worn a Buff.

If you can't find one at your LBS, they (or your local/chain outdoor outfitter) will definitely have balaclavas. That's my choice under a helmet - one that's stretchy enough that I can pull the eye hole under my chin when it warms up a little.

I think Buffs may be more versatile - they're so popular here - but balaclavas are easier to find.