You got to try it yourself.  I am a mitten man because I don't have very good circulation.  I also prefer the feel of mittens, any mitt with fingers on the inside is just garbage in my mind.  But if you have cold hands, something everyone should try before getting new gloves/mittens is just wearing a warmer jacket, or an extra layer.  If you're body is nice and toasty, than you're hands should be as well.