>>842668I think the most important part is fit and fleece weight (thickness). A form-fitting polar fleece does a better job keeping you warm than a baggy one will. I would also recommend against getting a composite jacket that has a layer for wind protection. It doesn't perform any better, and it is less versatile, than using a shell layer.
I also think there is some difference between the brands aside from different cuts (but some of the expensive ones are just charging for their branding). The largest difference is build quality of stitching and zippers. The material also makes a difference, but I think most are pretty similar. Any jacket using fabrics from Polar Tech should be great, but Polar Tech has different fabrics that are marginally better for certain uses. Overall though, the same fleece weight should give the almost the same insulation.
FWIW, I use a Norrona Trollveggen. The cut is perfect for me (long and slim), which can be difficult to find. There's probably better or cheaper out there there though.