No Question Baffle Box with hidden stitching..
Nowadays, premium quality products are only made with baffle box hidden stitching design.

It easy decision when thinking how to choose a down comforter.
The wise selection is the True Baffle Box with Hidden stitching. Best down comforter are made with this construction.   

Still, you have to check before buying a comforter because many sellers have not displayed correct information about the stitching construction and how made.

Compare Sewn-Through and Baffle Box Comforters.

The Sewn-Through Stitching construction is most used in today’s low-cost comforters. These types are less expensive comforters and the simplest way to manufacture them.

The two fabric layers were stitched together, and there was no isolation (no trapped air) just near the middle of the squares. The sewn-through creates heat and insulation lost between the stitching. These are called cold or hot spots.

Threads exposed on the surface easily break the sewing.
When you see threads on the pattern, that is the most significant sign to recognize the sew-through comforters.

The light, thin fabric under the minor stress at the stitching threads opening tiny holes gets dusting and losing the down in time. (that is why shorter warranty usually 2-5 years)

The visible box pattern stitching manufactured comforter is mainly used in the low cost down alternatives comforters like synthetic fiber fills or bamboo fiber comforters.
In this construction NO baffle box and cold spots all over the stitching lines.
The sewing through comforters is commonly used for summer comforters only with polyester fiber filling.

Sometimes these comforters look flat and hard to shake up without inside air streaming and remain flat with bad thermal isolation.

True Baffle Box or Baffle Wall stitching allows it to expand to a three-dimensional box that evenly distributes the down and isolates without any cold or hot spots. The unique ribbon closes the boxes from migrating the down ( down doesn’t shift) and at the same time allows it to rise almost twice higher than sewn-through comforters.

The baffle wall ribbon material allows air to stream inside the comforter to ensure an even temperature at any point. This airstream also helps to fluff up the comforter to maximum loft easily.