i would go with the bibs and parka because that way if your upper body gets warm and your legs are cold you can just take off the parka and still have layers to take off if you are still to warm or if your legs get warm you can just take off the bibs where as with coveralls you have to take off a whole layer of clothing causing one part of your body to become cold that is just my opinion i like this because it has worked for me so far just remember to dress in layers