I have little experience compared to the guys above, but I like the smaller, lighter blinds that are low profile. When you get out in the field, the lower profile ones stick out way less and I didn't mind a tight fit. I would be more concerned with being able to easily pack and conceal it than comfort, on really cold days I would just pack a cheap camping pad to put inside and lay on or heavier pants.
The bigger, roomier blinds are often harder to setup, harder to carry, much more expensive and stick out much more in the field.