Admittedly, I don't have to struggle quite so much with low temps as some of you guys, but my wife got me an Under Armour quarter-zip sweater that I really like when it gets down to the 50's or 60's but I'm still going to be fairly active. Very lightweight, very comfy. Spent most of last winter wearing it, but it was very mild last year. If it gets colder this year, might need to fish out my actual fleece.