There is really no one answer. If you tend to toss and turn a lot, then be prepared for a lot of drafts and lost heat with a quilt. For example, I have a neck injury that stiffens up after about 45 minutes to an hour. I need to roll over every 45 minutes or so. I don't have much luck with a quilt and below freezing.
If you remain in one position most of the night, then quilts let you get more use out of them, provided you have a good pad.
Compressed down does indeed have some insulating value, soo, it is kind of a mistake to discount it entirely. 3" of compressed down is roughly equivalent(at a guess) to about a 1/2" pad. It has the additional advantage of stopping drafts and leakage.