Easy days in the VERY cold tights warm up top and bottom or running shorts

Do you wear warm ups( like your team would wear to a meet and take off before the race) tights, or shorts? If it's real cold(8 degrees) and it's easy running, the warm ups are great for me because they have a under layer that keeps you warm. Your not looking to run fast, just stay warm. It's half tight or shorts with a good pair of longer unwear, the kind that look like tights.