I don't know if this is the warmest or best value,…
Source: bought it new
Price Paid: $60
I don't know if this is the warmest or best value, all I know is that I live in this in everything but the coldest winter.
Two years ago my wife and I decided to treat ourselves to fleeces, moving up from standard issue cotton sweatshirts. The difference is night and day and I rarely if ever wear the sweatshirts now.
The first time this fleece really proved valuable was after a fall snowstorm that left us without power for eight days and a dozen trees down on and around the house. Both my wife and I spent a weekend with a chain saw cutting and cleaning the neighborhood. At no point did I feel cold and I never got too hot either.
In colder winter or on rainy days I pair this fleece with a Gore-tex shell and I'm fine to drive the car or walk the dog in temperatures below 20°F. If I'm doing a more vigorous activity like hiking then the shell/fleece combo is good into the teens. The fleece alone was perfect this weekend on a three hour hike in the low 30s.
As I said above this was my first fleece so I don't know how it compares to others but this one has given me no problems in Tibet, the White Mountains, or cutting wood.