Like others have said, I personally don’t like how most duvet covers appear wrinkly and messy even if the comforter/duvet is properly secured to the cover. I lived with it for years but eventually, I gave up. For a while we slept with a top sheet, then a lightweight down quilted comforter with a quilt on top to give it a finished look. After constantly battling with a top sheet that would not stay secured/tucked in, I gave up on the top sheet. Fortunately my extra large capacity washer fits my king comforter so I just wash it regularly. In warmer months, when we go,to bed, I fold the quilt down as it is too hot to use in the summer.
My kids all have comforters with duvet covers. They never used top sheets (would find them shoved down to bottom of bed) so eventually I bought them all lightweight comforters from IKEA, two have IKEA duvet covers and two have covers I bought elsewhere. I don’t care about the messy duvet look in their rooms since half the time they don’t make their beds despite my nagging and they keep their doors closed when not home.
Eldest D is off to college in a few weeks-we are flying to her school. She desperately wanted this jersey duvet cover from Urban Outfitters that matches a wall tapestry she plans to hang (my niece has same duvet in diff color and my sister was raving about how soft and comfortable it is for teens who are always lounging on their beds). There is an IKEA nearby D’s university so we will pick up a lightweight down comforter to put inside the duvet cover when we get there.