So, my opinion is the comforter is more important than the cover. We have a Tommy Bahama Duvet and the one thing I learned was to mismatch the size of the cover and the size of the comforter. For years I could not figure out why our king comforter with duvet cover always seemed flat and the comforter always seemed to slide down inside the cover. Since my cover does not have the ties to tie the comforter inside, that made things worse. I previously used a king 750 fill pacific coast down comforter from costco inside my TB Duvet. About a few months ago, I purchased a (https://www.amazon.com/gp/product/B09B9YPB4X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1) 80% down 20% feather comforter, but the key was buying the palatial king which is 98 x 120. The fact that the comforter is larger than the standard king size duvet causes the duvet to fill up and give you that hotel luxury feel and regardless if you have ties on the inside of the duvet to keep the comforter in place, it says in place and maintains that puffed up quilted luxury feel. I would say the difference is remarkable and the comforter and duvet combination now is amazing. I know it isnt exactly what answer you were looking for, but I would worry about the comforter first and duvet second and talk a look at mismatching the size comforter to cover too.

https://www.amazon.com/dp/B09B9YPB4X?ref=ppx_pop_mob_ap_share

I got the pinch pleat palatial in white put it in a king duvet. For the price of the comforter, I was pretty impressed with the loft and quality not having to spend 600 on a down comforter that is a minimum of 80% down